Fixing leaks in LauncherPreview

> Do not add listeners when binding FolderIcon for preview
> Cleaning up preview object when the caller is no longer holding
  on to the communication channel for preview.

Bug: 393086035
Flag: EXEMPT bugfix
Test: Verified manually
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:986d7cb9c09a22915c922cf8e72c03ce36883742)
Merged-In: I4b758e6ce103c5201ef05ab824dd4e02f98c40b6
Change-Id: I4b758e6ce103c5201ef05ab824dd4e02f98c40b6