Fix RTL numbers in BlockedNumbersActivity

Phone numbers should always be LTR. Also removed layout_toStartOf since
it is redundant in LTR, and will cause phone numbers to align to
the left on RTL

RTL:
https://screenshot.googleplex.com/ZC7FpJp23ET
LTR:
https://screenshot.googleplex.com/hGoRSJjgyJ1
Before:
https://screenshot.googleplex.com/mt1XLgUusFX

Test: manual
Change-Id: I3381ecb229600563df8ca3dca4f7c1810f6e330d
Fixes: 30130422