Inline InputMethodSettings#isCurrentProfile()

With this commit,

  InputMethodSettings#isCurrentProfile()

is inlined into InputMethodManagerService without caching the result
of

  UserManagerInternal#getProfileIds(int userId, boolean enabledOnly)

for simplicity.

The observable behavior should semantically remain the same.

This is a preparation to decouple InputMethodSettings from
InputMethodManagerService global instance.

Bug: 309837937
Test: presubmit
Change-Id: I1c2659cd3c9c2c2908f1ae5be870052284d559c2