Use embedded VCS information rather than add manually

Arran Walkerrequested to merge
ajwalker/vcs-build into main

What does this MR do?

Uses the VCS information that Go adds to the binary, rather than setting it via LDFLAGS

What's the best way to test this MR?

  • Build the binary.
  • Execute ./gitlab-runner --version
  • Check

What are the relevant issue numbers?

Merge request reports