vscode-java/jdt.ls doesn't pick up settings changes if language server isn't running

This issue is a spinoff of #1672 which contains some more background information.

I encountered the following problem:

If you:

1. start vscode without starting the Java language server (e.g. folder without a pom.xml but with subfolders containing Java projects)
2. directly edit the java.* settings (e.g. java.home or java.configuration.runtimes) in settings.json
3. save the settings
4. open a Java file afterwards

the language server will start with the old settings and does not prompt you to clean the workspace. Your workspace will be out of sync with the settings and you'll need to manually clean the workspace.

Environment

• Operating System: MacOS 10.15
• JDK version: 11/15
• Visual Studio Code version: 1.50.1
• Java extension version: 0.69.0

Steps To Reproduce

see above in description