[7.3.0] Add path mapping test for multiplex sandboxing (#23134)

Javac actions gained support for multiplex sandboxing with rules_java
7.5.0, which makes it possible to test path mapping in this mode.

Fixes #21091

Closes #21837.

PiperOrigin-RevId: 657111790
Change-Id: Ib08f2c0bc48d210cce013e328da0e871f73278aa

Commit
https://github.com/bazelbuild/bazel/commit/8e79fe0329b995ec6db2f63d5cced84f90d158f3



Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>