CI cache creation failure should not fail a job

Summary

If creating a cache fails, the job should still succeed.

Steps to reproduce

Depends; the caching needs to fail for some reason.

What is the current bug behavior?

Failure to create a cache fails a job.

What is the expected correct behavior?

Caching is an optimization; it should not cause a job to fail (merely clear the cache instead, probably set the job status to warning or the like).