`TestSceneEditorTestGameplay` is not isolated from database, and one of
the tests exiting editor when seeked to 60000 milliseconds
(`TestClockTimeTransferIsOneDirectional()`) ended up changing
`EditorTimestamp` to the same value, causing
`TestSaveChangesBeforeGameplayTest()` to fail due to changing initial
state.
To fix, perform a direct deletion of imported beatmaps in realm to avert
this scenario, contrary to the soft-deletion via `BeatmapManager` done
previously.
I don't see an issue with applying this workaround to more places, even
though it is a workaround, because it marks each usage very clearly. If
we design a better solution in the future it should be easy to replace
the usages.