fix umgmt ListenAndServe to wait for the shutdown callbacks to execute
fix umgmt ListenAndServe to wait for the shutdown callbacks to execute

AndyDiamondstein/vitess,kuipertan/vitess,skyportsystems/vitess,netroby/vitess,cgvarela/vitess,alainjobart/vitess,xgwubin/vitess,dumbunny/vitess,apmichaud/vitess-apm,dumbunny/vitess,applift/vitess,dumbunny/vitess,anusornc/vitess,applift/vitess,dumbunny/vitess,ptomasroos/vitess,xgwubin/vitess,SDHM/vitess,applift/vitess,rnavarro/vitess,cgvarela/vitess,aaijazi/vitess,mapbased/vitess,sougou/vitess,HeisenbergUncertain/vitess,dumbunny/vitess,pivanof/vitess,dumbunny/vitess,SDHM/vitess,AndyDiamondstein/vitess,nurblieh/vitess,tirsen/vitess,applift/vitess,mlc0202/vitess,tjyang/vitess,cloudbearings/vitess,davygeek/vitess,enisoc/vitess,cgvarela/vitess,fengshao0907/vitess,fengshao0907/vitess,skyportsystems/vitess,tirsen/vitess,xgwubin/vitess,ngaut/vitess,dcadevil/vitess,cloudbearings/vitess,cloudbearings/vitess,nurblieh/vitess,applift/vitess,mapbased/vitess,rnavarro/vitess,HubSpot/vitess,SDHM/vitess,ptomasroos/vitess,kuipertan/vitess,mlc0202/vitess,mahak/vitess,yangzhongj/vitess,HubSpot/vitess,cloudbearings/vitess,aaijazi/vitess,pivanof/vitess,mapbased/vitess,fengshao0907/vitess,apmichaud/vitess-apm,yangzhongj/vitess,HubSpot/vitess,fengshao0907/vitess,mapbased/vitess,guokeno0/vitess,HeisenbergUncertain/vitess,yaoshengzhe/vitess,mapbased/vitess,erzel/vitess,tirsen/vitess,sougou/vitess,alainjobart/vitess,netroby/vitess,vitessio/vitess,tjyang/vitess,dumbunny/vitess,anusornc/vitess,rnavarro/vitess,skyportsystems/vitess,nurblieh/vitess,tinyspeck/vitess,kmiku7/vitess-annotated,sougou/vitess,davygeek/vitess,kmiku7/vitess-annotated,netroby/vitess,CERN-Stage-3/vitess,pivanof/vitess,yangzhongj/vitess,SDHM/vitess,mattharden/vitess,ptomasroos/vitess,vitessio/vitess,ngaut/vitess,atyenoria/vitess,tinyspeck/vitess,tinyspeck/vitess,rnavarro/vitess,yaoshengzhe/vitess,cgvarela/vitess,sougou/vitess,erzel/vitess,mahak/vitess,apmichaud/vitess-apm,mlc0202/vitess,AndyDiamondstein/vitess,xgwubin/vitess,netroby/vitess,kuipertan/vitess,skyportsystems/vitess,yaoshengzhe/vitess,mlc0202/vitess,applift/vitess,CERN-Stage-3/vitess,guokeno0/vitess,tjyang/vitess,mapbased/vitess,cgvarela/vitess,mlc0202/vitess,dumbunny/vitess,kuipertan/vitess,ptomasroos/vitess,yaoshengzhe/vitess,applift/vitess,HubSpot/vitess,AndyDiamondstein/vitess,dumbunny/vitess,ptomasroos/vitess,CERN-Stage-3/vitess,aaijazi/vitess,HubSpot/vitess,dcadevil/vitess,vitessio/vitess,alainjobart/vitess,cgvarela/vitess,erzel/vitess,davygeek/vitess,kuipertan/vitess,tirsen/vitess,AndyDiamondstein/vitess,skyportsystems/vitess,aaijazi/vitess,yangzhongj/vitess,erzel/vitess,kmiku7/vitess-annotated,tinyspeck/vitess,kmiku7/vitess-annotated,anusornc/vitess,nurblieh/vitess,alainjobart/vitess,AndyDiamondstein/vitess,rnavarro/vitess,mahak/vitess,michael-berlin/vitess,alainjobart/vitess,cloudbearings/vitess,aaijazi/vitess,tirsen/vitess,rnavarro/vitess,dcadevil/vitess,netroby/vitess,pivanof/vitess,mahak/vitess,yangzhongj/vitess,alainjobart/vitess,erzel/vitess,mapbased/vitess,HeisenbergUncertain/vitess,yaoshengzhe/vitess,xgwubin/vitess,guokeno0/vitess,mahak/vitess,fengshao0907/vitess,atyenoria/vitess,mattharden/vitess,atyenoria/vitess,tjyang/vitess,yaoshengzhe/vitess,guokeno0/vitess,netroby/vitess,tirsen/vitess,mapbased/vitess,ptomasroos/vitess,anusornc/vitess,kmiku7/vitess-annotated,cgvarela/vitess,vitessio/vitess,tjyang/vitess,fengshao0907/vitess,enisoc/vitess,yangzhongj/vitess,mattharden/vitess,mahak/vitess,skyportsystems/vitess,mattharden/vitess,guokeno0/vitess,dcadevil/vitess,xgwubin/vitess,guokeno0/vitess,sougou/vitess,davygeek/vitess,applift/vitess,mapbased/vitess,CERN-Stage-3/vitess,apmichaud/vitess-apm,xgwubin/vitess,kuipertan/vitess,mattharden/vitess,pivanof/vitess,michael-berlin/vitess,SDHM/vitess,rnavarro/vitess,atyenoria/vitess,michael-berlin/vitess,yaoshengzhe/vitess,cloudbearings/vitess,michael-berlin/vitess,xgwubin/vitess,ptomasroos/vitess,aaijazi/vitess,ptomasroos/vitess,cloudbearings/vitess,pivanof/vitess,guokeno0/vitess,applift/vitess,tinyspeck/vitess,mahak/vitess,vitessio/vitess,nurblieh/vitess,skyportsystems/vitess,mattharden/vitess,tirsen/vitess,yaoshengzhe/vitess,alainjobart/vitess,dcadevil/vitess,mlc0202/vitess,yaoshengzhe/vitess,tjyang/vitess,vitessio/vitess,skyportsystems/vitess,dumbunny/vitess,pivanof/vitess,erzel/vitess,erzel/vitess,fengshao0907/vitess,enisoc/vitess,nurblieh/vitess,atyenoria/vitess,kmiku7/vitess-annotated,yangzhongj/vitess,applift/vitess,enisoc/vitess,CERN-Stage-3/vitess,tjyang/vitess,SDHM/vitess,sougou/vitess,mlc0202/vitess,AndyDiamondstein/vitess,michael-berlin/vitess,SDHM/vitess,aaijazi/vitess,cgvarela/vitess,atyenoria/vitess,kmiku7/vitess-annotated,nurblieh/vitess,mattharden/vitess,kuipertan/vitess,michael-berlin/vitess,netroby/vitess,michael-berlin/vitess,michael-berlin/vitess,ngaut/vitess,erzel/vitess,rnavarro/vitess,HubSpot/vitess,yangzhongj/vitess,yangzhongj/vitess,nurblieh/vitess,mlc0202/vitess,tinyspeck/vitess,sougou/vitess,fengshao0907/vitess,davygeek/vitess,anusornc/vitess,erzel/vitess,davygeek/vitess,mlc0202/vitess,vitessio/vitess,skyportsystems/vitess,fengshao0907/vitess,kmiku7/vitess-annotated,mattharden/vitess,mattharden/vitess,enisoc/vitess,apmichaud/vitess-apm,anusornc/vitess,enisoc/vitess,SDHM/vitess,xgwubin/vitess,nurblieh/vitess,davygeek/vitess,atyenoria/vitess,pivanof/vitess,netroby/vitess,SDHM/vitess,michael-berlin/vitess,tinyspeck/vitess,cgvarela/vitess,anusornc/vitess,kuipertan/vitess,dcadevil/vitess,HubSpot/vitess,mapbased/vitess,atyenoria/vitess,anusornc/vitess,ptomasroos/vitess,netroby/vitess,guokeno0/vitess,tirsen/vitess,tirsen/vitess,aaijazi/vitess,alainjobart/vitess,tjyang/vitess,ngaut/vitess,sougou/vitess,cloudbearings/vitess,dcadevil/vitess,enisoc/vitess,erzel/vitess,HeisenbergUncertain/vitess,mahak/vitess,rnavarro/vitess,tjyang/vitess,mattharden/vitess,anusornc/vitess,aaijazi/vitess,guokeno0/vitess,cloudbearings/vitess,AndyDiamondstein/vitess,vitessio/vitess,pivanof/vitess,AndyDiamondstein/vitess,kuipertan/vitess,HubSpot/vitess,atyenoria/vitess,kmiku7/vitess-annotated,ngaut/vitess