[Contextual Edu] Only store keyboard shortcut time for All Apps

Only store keyboard shortcut time for gestures providing keyboard education
Currently only all apps provides keyboard shortcut education

Bug: 361279289
Test: KeyboardTouchpadEduInteractorTest
Flag: com.android.systemui.keyboard_touchpad_contextual_education
Change-Id: Iab050fc20db37663b38e3c26688c20f444cfd140