Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Upgrade bazlets to latest stable-2.15
  Bump required bazel version to 1.0.0rc2
  Upgrade bazlets to latest stable-2.14
  Upgrade testcontainers to 1.12.1

Change-Id: I010410b1e7797b5e4408adabee6fd9c8c7c7470e