fix: assign Zeebe role to demo user

[wollefitz]

Which problem does the PR fix?

Automatically assigns the Zeebe role to the demo seed user so that they can deploy to the Zeebe cluster by default.

Relates to https://github.com/camunda/web-modeler/issues/10572

What's in this PR?

Checklist

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[wollefitz]

@camunda/distribution Could you have a look at this PR?

[nithinssabu]

@camunda/distribution Could you have a look at this PR?

@camunda/distribution Can you please have a look at this PR?

[jessesimpson36]

I'm changing this to fix because I do not consider assigning a new role a "helm chart" feature. we have automation that bumps different version numbers because of "fix" or "feat" or "BREAKING CHANGE".