Fixed shortcut customizer layout issues when font size is max

When font size is set to max - the "Action +" text in the add shortcut
dialog was being cut-off and off-center. Also, in the case where
customization failed, error message was truncated.

Test: Manual- ensure that the scenarios above do not happen
Flag: com.android.systemui.keyboard_shortcut_helper_shortcut_customizer
Fix: 390072395
Change-Id: I728e6082814863a3b5cebf2ed997c82db8514859