Update OverviewCommandHelper to use Executors.MAIN to reduce the percentage of missed frames

This change will reduce the increase in the amount of missed frames measured by crystalball. I believe coroutines launch is competing with Executors.MAIN for scheduling and running tasks in the main thread, thus the increase in missing frames.

Fix: 366077002
Flag: com.android.launcher3.enable_overview_command_helper_timeout
Test: OverviewCommandHelperTest
Test: android.platform.test.scenario.launcher.CloseApp3ButtonModeMicrobenchmark#testOpenLauncher
Test: atp:v2/android-crystalball-eng/health/microbench/launcher/main/launcher-action-suite
Change-Id: I4477879d4f065ec3883f2c3cb3ef044e973ce0cb