Don't add removed messages to the heap

A message in the stack that is already marked for removal doesn't need
to be added to the heap. Its heap index is -1, so we won't attempt to
remove the not-in-heap message from the heap later.

Test: presubmit (FrameworksCoreTests_messagequeue)
Bug: 444085764
Bug: 444109907
Flag: build.RELEASE_PACKAGE_MESSAGEQUEUE_IMPLEMENTATION
Change-Id: I3f940eda440dd050b58cd117e83a3f5bebc1d1c9