Fix concurrent map read/write in rate limiter (#23958)

Signed-off-by: NCongqi Xia <congqi.xia@zilliz.com>

internal/proxy/multi_rate_limiter.go

@@ -70,6 +70,9 @@ func (m *MultiRateLimiter) Check(collectionID int64, rt internalpb.RateType, n i
 		return commonpb.ErrorCode_Success
 	}
 
+	m.quotaStatesMu.RLock()
+	defer m.quotaStatesMu.RUnlock()
+
 	limiter := m.collectionLimiters[collectionID]
 	if limiter == nil {
 		return commonpb.ErrorCode_Success