Revert "Use GestureDetector in WorkspaceTouchListener"

This reverts commit 7c8fb786.

Reason for revert: Chatted with Sunny, the concern was brought up that this is risky and will create potential for dogfood confusion with the new gesture navigation that is getting rolled out soon. So we can try to reland this in a few weeks.

Change-Id: I4f09cc9982164195dc42cd6e4714ede767cce786