Automatically prune content in the repository cache

### Description of the feature request:

Similar to https://github.com/bazelbuild/bazel/issues/5139, we'd like Bazel to be able to automatically prune the repository cache automatically to prevent it from filling the disk and requiring the user to clean out the cache to continue.

### What underlying problem are you trying to solve with this feature?

Multi-GB source tarballs that change frequently can fill the disk the repository cache resides on if they are downloaded by repository_rules, since the repository cache is not automatically cleaned out.

### Which operating system are you running Bazel on?

_No response_

### What is the output of `bazel info release`?

_No response_

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse master; git rev-parse HEAD` ?

_No response_

### Have you found anything relevant by searching the web?

https://github.com/bazelbuild/bazel/issues/5139 is the same idea for the disk portion of the combined remote cache.

### Any other information, logs, or outputs that you want to share?

_No response_

Start by reviewing the repository cache behavior described here and the related Bazel issue 5139. Determine the intended pruning policy and how frequently changing, multi-GB source tarballs should be handled. Done means the repository cache can automatically reclaim space without requiring users to clean it manually.

Written by the indexing model from the issue text.