Ensure proper canonical web url in Git over HTTP

Make sure that the current HttpServletRequest is propagated to
HttpCanonicalWebUrlProvider in Git over HTTP context. So that the output
of git push command has the proper server URL.

This also deletes the "manual injection" of
`Provider<HttpServletRequest>` from the `webInjector` in the `Daemon`
class. That injection doesn't make sense for this class, as
`HttpCanonicalWebUrlProvider` is not a singleton, which means a new
instance will be created each time it is obtained from Guice. So in the
`Daemon.java`, the instance will be created on the spot, then the HTTP
request provider will be set on it and that very instance will be
disposed.

This is fixing a problem encountered in the virutalhost plugin, where
despite proper configuration for tenant canonical web URL, the git push
output would use the value of `gerrit.canonicalweburl` configuration
option.

Bug: Issue 311925527
Release-Notes: Fix canonical web url binding in Git over HTTP
Change-Id: I82891b25bd23bb8467a2bb3fa829e58846140faf