Remove setIgnorePendingIntentCreatorForegroundState

The `setIgnorePendingIntentCreatorForegroundState` provides similar
funtionality as `setPendingIntentBackgroundActivityStartMode` which
is more versatile. The method is hidden and deprecated, so removal
should be safe.

Test: atest com.android.server.wm.ActivityStarterTests
Bug: 261780465
Change-Id: I5a4c433b78ff5e362f8d29e0723c3840643c4c5e