[test] Update status for some mirrors tests under reload stress testing.

Change-Id: Ia1b9adf1b83fe5cb5be8a853d1561fd1519f1df3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/116550
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

tests/lib_2/lib_2_kernel.status

@@ -68,9 +68,9 @@ isolate/pause_test: Skip # Timeout
 
 [ ($compiler == dartk || $compiler == dartkb) && ($hot_reload || $hot_reload_rollback) ]
 isolate/message4_test: Crash # Timeout and sporadic crash (issue 33824)
-mirrors/dynamic_load_test: Crash
-mirrors/library_uri_io_test: Skip # Timeout
-mirrors/library_uri_package_test: Skip # Timeout
+mirrors/dynamic_load_test: Skip # Reload has an effect similar to deleting the dynamically loaded library
+mirrors/immutable_collections_test: Pass, Slow
+mirrors/mirrors_reader_test: Pass, Slow
 
 [ $compiler == app_jitk || $compiler == dartk || $compiler == dartkb || $compiler == dartkp ]
 html/*: SkipByDesign