Use structural equality for A11yNodeInfo#mChildNodeIds

A11yNodeInfo#writeToParcel relied on LongArray#equals to avoid
storing it if it's the default value, but because the equality
is be by reference, it would store it every time.
This fixes that.

Test: a11y cts
Fixes: 72460870
Change-Id: I508df9e4346e304b8ae56cc38b17e9a940d941f1