Remove duplicated WM shell flicker service tests

Flicker service got paused mid-migration and we are running both legacy and flicker service version of the same tests, this cl removes the flicker service version to reduce resource usage as it doesn't add coverage

Bug: 311643481
Flag: TEST_ONLY
Test: atest WMShellFlickerTests
Change-Id: If6a0c44c8ddf9f133dd81d69c0609a9b6b162a41