Refactor ListGroup open close handling

[nikku]

Proposed Changes

• Previously we would render the list group items delayed, with old (outdated) items to be rendered against new model data (ref)
• This caused bugs in downstream dependencies (C7 properties panel breaks when template variable assignment is disabled camunda/camunda-modeler#4382)

This PR puts list group, on stable foundations, without magic ™️ ®️

Checklist

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• Brief textual description of the changes present
• Visual demo attached
• Steps to try out present, i.e. using the @bpmn-io/sr tool
• Related issue linked via Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}

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Related to camunda/camunda-modeler#4382

[barmac]

I tested this with bpmn-js-element-templates, and could not break it. Great improvement.

[barmac]

There's one thing which I don't get. After I link it, the placeholder tests in the bpmn-js-element-templates start to fail:

Chrome Headless 121.0.6167.85 (Mac OS 10.15.7) provider/cloud-element-templates - CustomProperties placeholder should display placeholder (FEEL, String) FAILED
	AssertionError: expected '' to deeply equal 'Placeholder'
	    at Context.eval (webpack-internal:///./test/spec/cloud-element-templates/properties/CustomProperties.spec.js:1662:36)
Chrome Headless 121.0.6167.85 (Mac OS 10.15.7) provider/cloud-element-templates - CustomProperties placeholder should display placeholder (FEEL, Text) FAILED
	AssertionError: expected '' to deeply equal 'Placeholder'
	    at Context.eval (webpack-internal:///./test/spec/cloud-element-templates/properties/CustomProperties.spec.js:1673:36)

It looks unrelated though.

[barmac]

This was due to an outdated @bpmn-io/feel-editor on my machine. This is good now.