[Storage] gsutil rsync failing to sync source with dangling symlink

[landscapepainter]

This PR closes #2147, which is initially raised by #2127

aws s3 sync is a command ran to sync Sky Storages set with s3/r2 storages. When the command sees a dangling symlink, it simply ignores and continue to sync other contents. However, gsutil rsync, which is used to set gcs, does not support this and fails early. In order to have consistent behavior between gcs and s3/r2 storages, I add an additional flag to the command to ignore all the symlinks in the source. Adding -e is the solution gsutil team provides to resolve dangling symlink issue. Also, as Sky Storage does not support symlinks, this is a suitable solution.

Tested (run the relevant ones):

• Manually ran gsutil -m rsync -erx to sync src with dangling symlink to gcs
• Relevant individual smoke tests: pytest tests/test_smoke.py::TestStorageWithCredentials
• Tested with pytest tests/test_smoke.py::test_gcp_storage_mounts

[romilbhardwaj]

Thanks! As we talked, you've also tested against yaml in #2127.
Recommend also running:

• pytest tests/test_smoke.py::test_gcp_storage_mounts

[romilbhardwaj]

Awesome! Thanks @landscapepainter!