[fenix] For https://github.com/mozilla-mobile/fenix/issues/13300 - Adjust the 'Sharing a Collection' layout to prevent overlapping of the close icon and 'Share' label in RTL

Note that the "Share" title is still constrained to start at the end of the
close button - I don't know why the previous extra constraint was causing the
differing behavior in LTR and RTL, but this seems to fix it.

app/src/main/res/layout/share_close.xml

@@ -22,7 +22,6 @@
         android:contentDescription="@string/content_description_close_button"
         android:padding="12dp"
         app:iconTint="@color/neutral_text"
-        app:layout_constraintEnd_toStartOf="@id/title"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent"
         app:srcCompat="@drawable/mozac_ic_close" />