Speed up and restore sync and upload_dir integration tests

[const-cloudinary]

Makes the sync and upload_dir integration tests wait for assets instead of sleeping, and runs all of TestCLISync again.

Brief Summary of Changes

• _wait_for_cld_files (test/test_modules/test_cli_sync.py): polls Search every 0.5s until the folder has the expected number of assets and exists (or is gone), and fails with the expected and found values after 15s. Used in setUp and after _upload_sync_files, replacing the fixed time.sleep calls and GRACE_PERIOD.
• TestCLIUploadDir: removes the 1s sleeps in setUp and tearDown.
• retry_assertion (test/helper_test.py): works as @retry_assertion and @retry_assertion(...), and runs tearDown and setUp between tries. The 9 decorated tests in TestCLISync now run their bodies.
• delete_cld_folder_if_exists in dynamic folder mode: deletes the assets found with Search, and lists them with the Admin API, folder by folder, when delete_folder reports that the folder is not empty.
• SyncDir.push and SyncDir.pull return True after transferring files, so sync prints "Done!" in that case too.
• test_cli_sync_duplicate_file_names_dynamic_folder_mode: expects the current "Local folder ... does not exist." log line.

What does this PR address?

• GitHub issue (Add reference - #XX)
• Refactoring
• New feature
• Bug fix
• Adds more tests

Are tests included?

• Yes
• No

Reviewer, please note:

• test_cli_sync.py takes longer than on master, because the 9 restored tests now upload and sync files. Tests that already ran are 3–6s faster each.
• Fixed folder mode cleanup is unchanged (prefix delete per resource type).

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I ran the full test suite before pushing the changes and all the tests pass.

Ran test_cli_sync.py and test_cli_upload_dir.py against a test cloud in dynamic folder mode: 31 of 32 passed. The remaining test passed on its own after updating its expected log line. Fixed folder mode is covered by CI only.

🤖 Generated with Claude Code