Merge branch 'stable-3.1'
* stable-3.1:
Upgrade bazlets to latest stable-3.1 to build with 3.1.7 API
CreateChangesTriggeringGc: Support existing project
Upgrade bazlets to latest stable-3.0 to build with 3.0.11 API
Remove the commented-out snapshot plugin api lines
Adapt SNAPSHOT plugin api example to the 3.1 version
Upgrade bazlets to latest stable-3.1
e2e Scenarios: Refine the gc checking resolution
Prepare for new gerrit_api snapshot version usage
Upgrade bazlets to latest stable-3.0
Upgrade bazlets to latest stable-3.0
CheckProjectStatisticsAfterGc: Make tests circular
Change-Id: I912453b22511f9ab395b50e6cd52befde2eb1701
