Fallback to 'direct' for GOPROXY when 'https://proxy.golang.org' is unavailable

What does this MR do?

This MR addresses the TLS handshake timeout error in GDK CI pipelines when Gitaly imports the Go module from proxy.golang.org. It sets the direct option as a backup for GOPROXY if the connection to https://proxy.golang.org fails.

For more details about this fallback option, see: https://github.com/golang/go/issues/37367.

cmd/gitaly-lfs-smudge/smudge.go:12:2: github.com/git-lfs/git-lfs/v3@v3.3.0: Get "https://proxy.golang.org/github.com/git-lfs/git-lfs/v3/@v/v3.3.0.zip": net/http: TLS handshake timeout
make[2]: *** [Makefile:623: /home/gdk/gdk/gitaly/_build/intermediate/gitaly-lfs-smudge] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [support/makefiles/Makefile.gitaly.mk:34: /home/gdk/gdk/gitaly/_build/bin/gitaly] Error 2
make: *** [support/makefiles/Makefile.timing.mk:4: gitaly-update-timed] Error 2

Related to gitlab-development-kit#1904 (closed)