SystemUI: Improve AOSP JA translation

Change-Id: Id2b979eae5c0c2f169f842ccdd2c5cf11a930a48
SystemUI: Remove unused strings

Change-Id: Ie8bf95abfeb4c13b30e9949aa9676ab39920bf29

Conflicts:

	packages/SystemUI/res/values/cm_strings.xml
core: Fix AOSP EL translation

* 'Minutes' was the same in singular & plural forms, fix that

Change-Id: I8444d879fa38fdbb9a89b96ff983c135cd0f3499