Reword "Keyboard" to "Keyboard layout"

Someone thought that “keyboard” was referring to the type of keyboard (USB, BlueTooth) or drivers, etc. Using “Keyboard layout” which is a more common phrasing might help.

Feature Branch: greeter:feature/revamp_phase1

Parent Task: #10812 (closed)

Original created by @alant on 10816 (Redmine)

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