Language client still used for "quick fixes" after turning qmlls off

Follow the instructions from QTCREATORBUG-31977

• have usage of QML language server turned on in the settings
• open a QML file and e.g. add "Item {}"
• try to trigger refactorings with e.g. alt+enter on "Item"
• popup doesn't show (that's the other bug)
• now go to the settings and turn off usage of qmlls
• alt+enter still doesn't show a popup
• close the file and reopen
• alt+enter now works

Debugging shows that LanguageClientQuickFixProvider is still used after turning qmlls usage off. Closing and reopening the file mends that.