Grails: IDE does not recognize a project with Grails 6 when Grails Shell is absent

***What steps will reproduce the issue?***
1\. Create a grails project with version 6.0.0
2\. Open the project with intellij idea ultimate

***What is the expected result?***

That the project was recognized as a grails project and the player button worked.

***What happens instead?***

When opening a project with grails 6 intellij does not recognize the project as a grails project.

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*Imported from [IDEA-327614](https://youtrack.jetbrains.com/issue/IDEA-327614) · Type: Bug · Votes: 6*
*Comments, attachments, dates and reporter are not part of the export — follow the link above for the full history.*

Reproduce the issue with a Grails 6.0.0 project opened in IntelliJ IDEA Ultimate without Grails Shell. Start by tracing the plugin's project-recognition entry point and the player-button integration; done when the project is recognized as a Grails project and the player button works.

Written by the indexing model from the issue text.