Revert "Handle uiMode changes in QuickstepLauncher"

Revert submission 27627108-b/339747262

Reason for revert: b/353914086
Fix: 353450667
Fix: 353914086
Bug: 339747262

Reverted changes: /q/submissionid:27627108-b/339747262
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:2676385eb81b7048c8f169ebf3b80b695103e952)
Merged-In: I9a71ee0fa4062b15e68eff41951f42d46ace19d3
Change-Id: I9a71ee0fa4062b15e68eff41951f42d46ace19d3