feat: add go http_request tests

[daniel-sanche]

• adds tests that http requests are sent in the proper format (related bug: https://github.com/googleapis/google-cloud-go/pull/7083)
• fixes the go local test target, to use modified container building function used by other go env tests.
  • previously the test wasn't using the local library version
• environment tests use env var project id when provided, rather than checking with the metadata server