SystemUI: Fix QS clock overlapping on UI mode change

Calling updateAnimators() in a separate runnable seems to
cause QSB header elements to overlap each other when switching
between dark and light mode. This change was introduced in
https://github.com/LineageOS/android_frameworks_base/commit/0558e1211604b3b6f465a394832bbf8fa06d1dfe and seems unnecessary so lets revert it.

Change-Id: I14e60b608f2aac373e71fec0a6ab7d8e787d2457