Allow Meta+Ctrl+Backspace for bug report for user builds

AL provides the Bug handler for user builds so need a shortcut
to fire it on user builds. For AOSP, we don't provide a bug
handler app in user build, and will do nothing. OEMs already have
config to enable/disable bug handling and it will respected for
the shortcut.

Bug: 431248889
Test: Presubmit
Flag: EXEMPT bugfix
Change-Id: I2099da8e285f6280ea7f7e15211a7e00372e14ad