Fix settings slice caching

Previously if there were multiple clients it would trigger an infinite
loop as the cache gits dropped after the first bind, and the second
client would trigger another load. Instead now cache as long as slices
are pinned since thats the intended behavior of caching.

Test: make RunSettingsRoboTests
Change-Id: I7d29fab87573120b34cd55e1696c4c5b70fc891c
Fixes: 78471335