Remove deprecated overridden method

Author: tstirrat15

src/main/java/com/authzed/grpcutil/BearerToken.java

@@ -32,9 +32,4 @@ public void applyRequestMetadata(RequestInfo requestInfo, Executor executor, Met
             }
         });
     }
-
-    @Override
-    public void thisUsesUnstableApi() {
-        // Intentionally empty
-    }
 }