pkg/vm_service/test/{set_breakpoint_state,user_tag_changed}_test timing out on unittest-asserts-release-mac-arm64

[sstrickl]

There are new test failures on Fix the extract method refactoring to correctly handle nullable return types...[pkg/dart2native] switch to use package:lints.

The tests

pkg/vm_service/test/set_breakpoint_state_test Timeout (expected Pass)
pkg/vm_service/test/user_tag_changed_test Timeout (expected Pass)

are failing on configurations

unittest-asserts-release-mac-arm64

The former went from RTE -> Timeout, the latter is a new test. The logs are here.

/cc @bkonyi

[alexmarkov]

pkg/vm_service/test/user_tag_changed_test started passing and them timed out once again.

https://dart-ci.appspot.com/log/pkg-mac-release-arm64/unittest-asserts-release-mac-arm64/19/pkg/vm_service/test/user_tag_changed_test

[whesse]

These two test failures are flaky, but not detected as flaky on individual builds. Manually added flakiness records for them, so they stop appearing as switching between Pass and Timeout.

The failures still exist, so leaving the bug open.