vtctld2: Serve index.html only for extensionless files at root.
vtctld2: Serve index.html only for extensionless files at root.

We need to serve index.html for virtual routes like /dashboard and
/keyspace, but we shouldn't serve it if the URL is trying to access an
actual file that happens to not exist.

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