NSSL: requestLayout on split shade change

Since the side padding can change based on the split shade state, and
since the split shade state can change independently of configuration
changes, and since I'm just kinda skeptical of the sequence of events
here, explicitly request a layout pass when the split shade state
changes.

Bug: 328588062
Test: postsubmit
Flag: NA
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:047546e21f8ccabc412237a353e0de2b10c43328)
Merged-In: I8c472541ad4c9115480100cf6c05ab02f09f198e
Change-Id: I8c472541ad4c9115480100cf6c05ab02f09f198e