Remove unnecessary invocation of updateRotation

mMultiuserReceiver#onReceive will call mSettingsObserver.onChange.
But both mSettingsObserver#updateSettings and
mDefaultDisplayRotation.onUserSwitch() in
mMultiuserReceiver#onReceive already check if there is something
needs to update rotation. So it is unnecessary to call
updateRotation again in mSettingsObserver.onChange.

Cherry picked Ic201f319739e910bfb7bf4c9c55a9d687b35cb78 to master due to b/286408867.

Code was merged via `-s ours` and is missing even though the sha exists on the target branch. Cherry pick is required to bring in the code.

Manually remove the "Merged in" directive to allow for downstream propagation.

Bug: 197745994
Test: Switch user
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:a1c3f60121762a349e802011c764ebaa3b019b1b)
Change-Id: If93b63417b526d8774b10f263eb4c4810a70cabe