Revert "Introduce per-user InputMethodSettings cache"

This reverts commit 90622cfcc48b115f6ccab469dd23bccc6d01a965.

This fixes a lock contention that added a regression in boot time.

Fix: 329414077
Bug: 309837937
Test: n/a
Change-Id: I1e6caa541620523ffdd611042c80a3b2562ae0be
3 files changed