Current code only updates the text on the "not charging" condition, causing the tooltip
display to get out of sync with the rest of the applet once charging begins. This patch
This is a bugfix for a bug that affects Plasma 5.18, but fixing it requires introducing a
new string. As such, I am targeting 5.19, but if the Localization team approves, I can
land this on the stable branch if it's accepted.