docker: lite image: Copy only the "app" directory for vtctld2.
docker: lite image: Copy only the "app" directory for vtctld2.

This reduces the size of the lite image from 281 MB to 215 MB.

tirsen/vitess,sougou/vitess,davygeek/vitess,mattharden/vitess,mattharden/vitess,enisoc/vitess,HubSpot/vitess,enisoc/vitess,sougou/vitess,pivanof/vitess,sougou/vitess,alainjobart/vitess,rnavarro/vitess,alainjobart/vitess,davygeek/vitess,tirsen/vitess,pivanof/vitess,mattharden/vitess,pivanof/vitess,HubSpot/vitess,davygeek/vitess,dcadevil/vitess,pivanof/vitess,alainjobart/vitess,rnavarro/vitess,rnavarro/vitess,mahak/vitess,mahak/vitess,mapbased/vitess,tirsen/vitess,vitessio/vitess,vitessio/vitess,tinyspeck/vitess,rnavarro/vitess,tinyspeck/vitess,mapbased/vitess,pivanof/vitess,sougou/vitess,applift/vitess,pivanof/vitess,tinyspeck/vitess,dcadevil/vitess,dcadevil/vitess,mattharden/vitess,mattharden/vitess,alainjobart/vitess,vitessio/vitess,mahak/vitess,rnavarro/vitess,tirsen/vitess,pivanof/vitess,tirsen/vitess,vitessio/vitess,tirsen/vitess,mahak/vitess,vitessio/vitess,enisoc/vitess,tirsen/vitess,enisoc/vitess,applift/vitess,mapbased/vitess,applift/vitess,enisoc/vitess,mahak/vitess,alainjobart/vitess,mapbased/vitess,alainjobart/vitess,tirsen/vitess,davygeek/vitess,HubSpot/vitess,dcadevil/vitess,sougou/vitess,HubSpot/vitess,sougou/vitess,applift/vitess,tinyspeck/vitess,mahak/vitess,mapbased/vitess,mattharden/vitess,applift/vitess,pivanof/vitess,tinyspeck/vitess,mapbased/vitess,vitessio/vitess,applift/vitess,enisoc/vitess,mattharden/vitess,vitessio/vitess,mahak/vitess,dcadevil/vitess,HubSpot/vitess,HubSpot/vitess,HubSpot/vitess,sougou/vitess,dcadevil/vitess,vitessio/vitess,mapbased/vitess,alainjobart/vitess,mattharden/vitess,sougou/vitess,mapbased/vitess,rnavarro/vitess,HubSpot/vitess,mattharden/vitess,rnavarro/vitess,mattharden/vitess,applift/vitess,mapbased/vitess,pivanof/vitess,tinyspeck/vitess,rnavarro/vitess,tirsen/vitess,applift/vitess,alainjobart/vitess,applift/vitess,mapbased/vitess,dcadevil/vitess,davygeek/vitess,rnavarro/vitess,tinyspeck/vitess,mahak/vitess,enisoc/vitess,davygeek/vitess,applift/vitess,davygeek/vitess