perf(Storage): Optimize CRC32C interceptor with ReferenceEquals check for uploadUri

This change introduces a ReferenceEquals check for the _uploadUri.
Since URI objects are typically stable during the request lifecycle,
this provides an O(1) fast-path to bypass the interceptor logic
for unrelated traffic, minimizing service-wide latency.

- Added ReferenceEquals check for immediate filtering
- Reduced CPU cycles for non-upload service calls
- Addressed PR feedback regarding parallel request overhead

Author: mahendra-google

apis/Google.Cloud.Storage.V1/Google.Cloud.Storage.V1/CustomMediaUpload.cs

@@ -68,7 +68,7 @@ public Crc32cHashInterceptor(CustomMediaUpload mediaUpload, HashingStream hashin
 
             public Task InterceptAsync(HttpRequestMessage request, CancellationToken cancellationToken)
             {
-                if (_uploadUri == null || !_uploadUri.Equals(request.RequestUri))
+                if (_uploadUri == null || (!ReferenceEquals(_uploadUri, request.RequestUri) && !_uploadUri.Equals(request.RequestUri)))
                 {
                     return Task.CompletedTask;
                 }