Be resilient to outdated exec paths in action cache entries (#23269)

https://github.com/bazelbuild/bazel/commit/60924fdc2972184494f6382d39e8c786aa14b9a9
changed the canonical repo name separator from `~` to `+`. Older repo
names containing `~` now trigger a syntax error. If an action cache
entry refers to an exec path from a previous version of Bazel that used
`~`, we need to be resilient and treat the cache entry as corrupted,
rather than just crash.

Fixes https://github.com/bazelbuild/bazel/issues/23180

.

Closes #23227.

PiperOrigin-RevId: 660105601
Change-Id: Iea5d86c635056d12ba20598383da463bdde03ab0

Co-authored-by: Xdng Yng <wyverald@gmail.com>