[flexiglass] Avoid reloading drawable if LayoutDirection didn't change

onRtlPropertiesChanged calls updateDrawable even for the first time,
when the initial call to onRtlPropertiesChanged would make a redundent
call to updateDrawable (because the layout direction already used when
the icon was set is the same as the one received by
onRtlPropertiesChanged).

This change skips reloading the same icon in these cases.

Bug: 410757909
Test: switched between RTL and LTR and posted a notification with an
autoMirrored icon to the status bar to make sure that it gets reversed
in the status bar
Flag: com.android.systemui.scene_container

Change-Id: Ieb2aada3816d48f66422ecefc017bac8e9f683c3