Check DISALLOW_ADJUST_VOLUME in the Modes tile, same as the DND tile did

Technically, some modes may not adjust volume. But since we disable the whole Modes page in Settings, it's consistent to do the same here.

Fixes: 417390373
Test: atest ModesTileTest + manual
Flag: EXEMPT Trivial bugfix
Change-Id: Ia21bc336427bf16c05cc4d557edf1364d70ef82c