This commit removes the entire GMA C++ SDK from the Firebase C++ SDK, including all references to it across all platforms (iOS, Desktop, and Android).

Changes include:
- Deletion of the core `gma` directory and its contents.
- Removal of GMA from CMakeLists.txt files.
- Removal of GMA from Gradle build files.
- Removal of GMA from iOS Podfiles.
- Removal of GMA from integration tests and UI tests.
- Removal of GMA from build scripts and CI workflows.
- Updates to documentation (README.md, Doxyfile) to reflect the removal, while preserving release notes related to past GMA versions and adding a new note about its removal.

This commit removes the explicit print statement when skipping GMA-related
encrypted files in `scripts/gha/restore_secrets.py`. The script will
now silently ignore these files, aligning with the complete removal of
the GMA SDK and avoiding unnecessary log output.

This commit ensures that `scripts/gha/restore_secrets.py` correctly
skips processing for any GMA-related encrypted files. The existing
check `if api == "gma": continue` should prevent attempts to write
decrypted secrets to the `gma/integration_test` directory, which no
longer exists after the removal of the GMA SDK.

This submission is to confirm the CI tests against this version of the
script.

This commit further refines `scripts/gha/restore_secrets.py` to prevent
attempts to write to the deleted `gma/integration_test` directory.

Changes include:
- Initializing `dest_paths` as an empty list.
- More careful construction of `dest_paths` based on whether `FLAGS.artifact`
  is set, ensuring that GMA paths are not inadvertently created.
- Explicitly continuing the loop if no valid destination path is determined
  for a file, preventing unnecessary decryption or write attempts.
- Adding redundant checks to ensure GMA paths are not processed before file
  write operations as a final safeguard.

This should robustly address the `FileNotFoundError` previously observed in CI.

This commit removes print statements from `scripts/gha/restore_secrets.py` that were logging potentially sensitive file paths. This addresses security alerts raised by the GitHub Advanced Security bot regarding clear-text logging of sensitive information.

This commit simplifies the removal of the GMA SDK by deleting the
`scripts/gha-encrypted/gma` directory entirely. This is a cleaner
solution than adding skip logic to `restore_secrets.py` and resolves
the `FileNotFoundError` in the CI by removing the source of the problem.

The `restore_secrets.py` script has been reverted to its original state.

This commit ensures the complete removal of the GMA SDK by forcefully
deleting the `scripts/gha-encrypted/gma` directory. This is the root
cause of the `FileNotFoundError` in the CI and is the cleanest solution.

The `restore_secrets.py` script remains in its original state, as the
problem is resolved by removing the gma secrets it was attempting to process.