It seems that we spawn too many qmlls instances after changing settings.
Reproduction steps:

• Create new Qt Quick project
• Add 5 .qml files, and open them
• Change the qmlls settings at Preferences > Language Clients > QML Language Server (check or uncheck any box)
• click on the language server button in the qml editor
  expectations: there should be one qmlls running for each build configuration.
  Actual outcome: There is one qmlls running per opened file for each build configuration, so if you have one build configuration, you should see 5 qmlls instances.