[GCP Observability C++] Increase deadline for MetadataQuery requests (#32762)

Fixes b/276092199. Stanley noticed that EnvironmentDetection requests
were timing out, so increasing the deadline.
<!--

If you know who should review your pull request, please assign it to
that
person, otherwise the pull request would get assigned randomly.

If your pull request is for a specific language, please add the
appropriate
lang label.

-->

src/cpp/ext/gcp/environment_autodetect.cc

@@ -304,7 +304,7 @@ class EnvironmentAutoDetectHelper
               on_done(std::move(resource).value());
             }
           },
-          grpc_core::Duration::Seconds(1)));
+          grpc_core::Duration::Seconds(10)));
     }
   }