[firebase-release] Removed change log and reset repo after 14.9.0 release

Author: google-oss-bot

CHANGELOG.md

@@ -1,5 +0,0 @@
-- Added validation to check if project ID exists during project creation. (#5233)
-- Added `generate_dataconnect_schema`, `dataconnect_generate_operation`, `firebase_consult_assistant` MCP tools. (#8647)
-- `firebase init dataconnect` is now integrated with Gemini in Firebase API to generate Schema based on description. (#8596)
-- Added user-friendly warning for runtime errors from the GCF API. (#8713)
-- Updated Data Connect emulator to 2.8.0, which adds a README to generated Kotlin packages and drops support for macOS 10.15 (Catalina).