Merge branch 'stable-3.4' into stable-3.5

* stable-3.4:
  Split integrations tests into separate Bazel targets.
  Extract base test class for regular and async acceptance tests
  Allow additional refs fallback to apply-objects
  Stop creating redundant replication tasks from stream-events
  Add event creation time to the apply object payload
  Don't read git submodule commits during replication
  Expose implicit dependency with the multi-site plugin
  Ignore remote ref-updated stream events for replication
  Increase test time to 900 seconds

Change-Id: I7b98c49d875e4f2917af21abec562a21582f6b28