Add E2E test for unlink and unlinkat

[t4lz]

There are hooks for unlink and unlinkat, as far as I can see those hooks are not tested anywhere.
We should add an E2E test (or add them to an existing test, doesn't matter), and test for each of the two:

• calling on a remote path (i.e. a path that is configured to be written remotely)
• calling on a relative path (should be bypassed)
• calling on a local path (i.e. a path that is supposed to be bypassed by mirrord)
• calling on a mapped path (i.e. a path that is configured to be mapped to a different path)

[linear]

MBE-725 Add E2E test for unlink and unlinkat