[CI] Migrate monolithic-linux script to sccache
This is in preparation for migrating to Google Cloud Storage (GCS) based
caching soon which is only supported by sccache.
Reviewers: Keenuts, gburgessiv, dschuff, lnihlen, cmtice
Reviewed By: cmtice
Pull Request: https://github.com/llvm/llvm-project/pull/149195
