Disable the trustedOverlay flag for taskview

- TaskView is meant to contain app activities which shouldn't have
  trusted overlay set even when itself placed in a window which is
  trusted.

Fix: 339701674
Fix: 342050101
Bug: 320410671
Test: atest WindowUntrustedTouchTest
Change-Id: Ib9e3c73516aba7f407e8bcbf8cb9cd7477f40fa8