Prevent setting pending bind if we are bound

If we are bound (or in the process of binding) do not set pending bind
again. This could happen if we are trying to bind shortly after the tile
was added, as that flow involves a temporary bind.

This was causing the tiles to show as Unavailable and preventing clicks
on them when `qs_new_tiles` flag was on.

Test: atest --iterations 20 CtsTileServiceTestCases with flag on and off
Test: atest TileServiceManagerTest
Fixes: 344449464
Flag: EXEMPT bugfix
Change-Id: I95108c24ef61127c99d8006354a30b993ba65c9f