Fixes canEnableDisableInputMethod to use correct user handle.

The old logic was grabbing the user handle while inside a block that
cleared user identity, so the user handle always returned 0 instead of
the correct user handle.

Fix: 375119534
Test: follow steps in the bug on an HSUM device
Test: atest --user-type secondary_user AccessibilityServiceConnectionTest
Flag: EXEMPT minor bugfix
Change-Id: Id86264284bdfec0b436c01335d979087a8fd099a