Perform minor code clean up

Clean up:
* Removed unused local variable (focusWindowClient) in #dumpAsStringNoCheck
* Removed unnecessary fully qualified name 'ImeVisibilityStateComputer.STATE_HIDE_IME' due to existing static import.
* Remove the static import for both STYLUS_HANDWRITING_DEFAULT_VALUE and STYLUS_HANDWRITING_ENABLED with direct references from Settings.Secure. This will ensure consistency in how settings are accessed.

Bug: 339089063
Test: m
Flag: EXEMPT refactor
Change-Id: Ic786df7c7c9c2e730819f666a2d68861c0ba63a0