Add missing unit for signal strength (#40436)

* Added missing unit for signal strength

* Added one more unit

* Replaced string with variable

* Fixed wrong import

* Fix import

* Replaced string with variable

* Fixed wrong import

* Apply suggestions from code review

* Black

* Again a fix :-(

* iSort

* iSort after merge

Co-authored-by: springstan <46536646+springstan@users.noreply.github.com>