Update testGetGameModeInvalidPackageName test

Previously this test verifies if the permission
permission.MANAGE_GAME_MODE is granted, which is already tested
in a separate test case. This patch updates the test to match
the test name.

Bug: 264528460
Test: atest GameManagerServiceTests
Change-Id: Ie4a8645633edc6aa32458571e2cc54f0ac5222e9