Dropping 2.12 support for workbench-google2

[Qi77Qi]

Services depends on workbench-google2 that have migrated to Scala 2.13

• Leonardo
• Rawls (note rawls-model is already cross publishing to 2.13)
• Depends on Cromwell
• Agora
• Sam

Cromwell, Orchestration don't depend on workbench-google2. Relevant thread.

Related PR

• [no ticket] Drop 2.12 for notification, errorReporting, openTelemetry modules #461

Plan for Rawls if it can't be upgraded to 2.13 anytime soon

• Rawls can continue to use the last version that supports 2.12
• If Rawls has any new features that we need. Publish a 2.12 version with relevant change explicitly. This will require some extra work, but should be possible.