Automerge: [CI][Github] Use newer sccache version in CI container

I was having trouble with the version that ships in the ubuntu apt repository
and GCS based caching. The newer version works, so reintroduce the infra that
we had in 2c1d4b0 to download it.

Reviewers: tstellar, lnihlen, gburgessiv, dschuff, cmtice, Keenuts

Reviewed By: cmtice, Keenuts

Pull Request: llvm/llvm-project#149196

Author: boomanaiden154