[gardening] Skip isolate_group_shared_callback_test on hot reload bots.

The test in reload is very slow in "--shared_slow_path_triggers_gc" configuration.

Fixes #60758
TEST=ci

Change-Id: I16e9ff1de273464a866db6db8fa839b7aa03dca8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430882
Reviewed-by: Siva Annamalai <[email protected]>
Commit-Queue: Alexander Aprelev <[email protected]>

Author: aam

tests/ffi/ffi.status

@@ -109,3 +109,6 @@ callback_unwind_error_test: Crash # https://github.com/dart-lang/sdk/issues/3948
 
 [ $sanitizer == asan || $sanitizer == msan || $sanitizer == tsan ]
 data_not_asan_test: SkipByDesign # This test tries to allocate too much memory on purpose.
+
+[ $hot_reload || $hot_reload_rollback ]
+isolate_group_shared_callback_test: SkipSlow # shared_slow_path_triggers_gc in combination with reload makes this test very slow