Changed layout of dialogs for a11y

Changed the custom label dialog and create group
label dialog to fix accessibility scanner complaints.
Accessibility scanner still complains about edit field
hint on create new label dialog but i could not repro
any issues and talkback read the hint as intended.

Test: Verified text boxes are showing and talkback is working
properly. Also verified that all other accessibility scanner
suggestions are fixed.

Bug: 29216746

Change-Id: Ib5f10eefab0911ad499be0d2c1c1ad7d3dc33a33