examples/local: Fix vttablet-up.sh for empty $tablet_hostname.
examples/local: Fix vttablet-up.sh for empty $tablet_hostname.

alainjobart/vitess,mahak/vitess,dcadevil/vitess,davygeek/vitess,enisoc/vitess,applift/vitess,davygeek/vitess,rnavarro/vitess,erzel/vitess,AndyDiamondstein/vitess,tinyspeck/vitess,aaijazi/vitess,AndyDiamondstein/vitess,guokeno0/vitess,aaijazi/vitess,pivanof/vitess,mapbased/vitess,mapbased/vitess,mattharden/vitess,dumbunny/vitess,mattharden/vitess,mapbased/vitess,pivanof/vitess,erzel/vitess,mapbased/vitess,dcadevil/vitess,applift/vitess,HubSpot/vitess,mapbased/vitess,mapbased/vitess,dumbunny/vitess,aaijazi/vitess,HubSpot/vitess,erzel/vitess,mattharden/vitess,vitessio/vitess,sougou/vitess,sougou/vitess,vitessio/vitess,vitessio/vitess,tirsen/vitess,AndyDiamondstein/vitess,aaijazi/vitess,aaijazi/vitess,mattharden/vitess,tirsen/vitess,sougou/vitess,mahak/vitess,vitessio/vitess,rnavarro/vitess,dumbunny/vitess,dcadevil/vitess,guokeno0/vitess,sougou/vitess,pivanof/vitess,dumbunny/vitess,rnavarro/vitess,sougou/vitess,AndyDiamondstein/vitess,tirsen/vitess,tinyspeck/vitess,alainjobart/vitess,vitessio/vitess,AndyDiamondstein/vitess,applift/vitess,mapbased/vitess,tirsen/vitess,mapbased/vitess,alainjobart/vitess,erzel/vitess,applift/vitess,mahak/vitess,tirsen/vitess,dumbunny/vitess,alainjobart/vitess,mattharden/vitess,guokeno0/vitess,AndyDiamondstein/vitess,tinyspeck/vitess,rnavarro/vitess,applift/vitess,mahak/vitess,pivanof/vitess,guokeno0/vitess,rnavarro/vitess,mattharden/vitess,AndyDiamondstein/vitess,dcadevil/vitess,dumbunny/vitess,guokeno0/vitess,sougou/vitess,dcadevil/vitess,erzel/vitess,vitessio/vitess,HubSpot/vitess,sougou/vitess,applift/vitess,tirsen/vitess,tirsen/vitess,vitessio/vitess,alainjobart/vitess,applift/vitess,applift/vitess,erzel/vitess,mahak/vitess,aaijazi/vitess,davygeek/vitess,mapbased/vitess,erzel/vitess,sougou/vitess,aaijazi/vitess,enisoc/vitess,applift/vitess,guokeno0/vitess,HubSpot/vitess,AndyDiamondstein/vitess,mattharden/vitess,davygeek/vitess,pivanof/vitess,dcadevil/vitess,vitessio/vitess,mahak/vitess,dumbunny/vitess,enisoc/vitess,HubSpot/vitess,mattharden/vitess,erzel/vitess,erzel/vitess,rnavarro/vitess,rnavarro/vitess,enisoc/vitess,davygeek/vitess,aaijazi/vitess,dumbunny/vitess,mapbased/vitess,tirsen/vitess,tinyspeck/vitess,tinyspeck/vitess,davygeek/vitess,dcadevil/vitess,guokeno0/vitess,mahak/vitess,pivanof/vitess,rnavarro/vitess,dumbunny/vitess,tinyspeck/vitess,AndyDiamondstein/vitess,guokeno0/vitess,enisoc/vitess,davygeek/vitess,applift/vitess,dumbunny/vitess,guokeno0/vitess,erzel/vitess,aaijazi/vitess,tinyspeck/vitess,HubSpot/vitess,mahak/vitess,enisoc/vitess,rnavarro/vitess,alainjobart/vitess,mattharden/vitess,HubSpot/vitess,HubSpot/vitess,enisoc/vitess,pivanof/vitess,alainjobart/vitess,pivanof/vitess,mattharden/vitess,alainjobart/vitess,pivanof/vitess,tirsen/vitess