Remove @hide ACTION_SHOW_INPUT_METHOD_PICKER

All references to
android.provider.Settings.ACTION_SHOW_INPUT_METHOD_PICKER have been
removed by the following CLs.

 Id36c8c34159bea8b72557b40bcf024d401f580b6 frameworks/base
 Id990c66516c9b3ed7ada6891746ec0e0eecbe545 packages/apps/Settings
 I915231678b94f97c1b5105cb607d6631e3df6b6a vendor/google_clockworks
 I3e26ed807445725262485ac1065fdfa299d1b624 cts

Test: make checkbuild
Fixes: 64008672
Bug: 6364455
Change-Id: I4210a5b5662be497d395a454f7f1cc395637683e