Revert "stop testing Gerrit on macOS; It hardcodes python2 which is generally not available on macOS."
Revert "stop testing Gerrit on macOS; It hardcodes python2 which is generally not available on macOS."

This reverts commit 7895accf5b2c68c5f20a5393ab70f741b4845197.

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration