tools: remove unused gflags module
Its only dependant was closure-linter but that was removed in commit f9dd34d3 ("tools: replace closure-linter with eslint"). Remove it.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Its only dependant was closure-linter but that was removed in commit f9dd34d3 ("tools: replace closure-linter with eslint"). Remove it.