fix: cap distinct user-agents per endpoint in GrpcUsageTracker - #26778

 95 files  ±0   95 suites  ±0   1h 9m 35s ⏱️ - 16m 47s
151 tests ±0  151 ✅ ±0  0 💤 ±0  0 ❌ ±0 
673 runs  ±0  673 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit eb695f6. ± Comparison against earlier commit b7a4df6.