fix: restrict mime type list depending on check operator

[R0Wi]

• Resolves: #23666

Summary

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• [ ] Tests (unit, integration, api and/or acceptance) are included
• [ ] Screenshots before/after for front-end changes
• [ ] Documentation (manuals or wiki) has been updated or is not required
• [ ] Backports requested where applicable (ex: critical bugfixes)

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[R0Wi]

@blizzz I rebased this against the current master and adjusted to code to work with c24ead810de180727ffbb9122bfe027e94fdd964.

Would be happy to see a review of this since me and other users are stumbling across the described issue regularly :smile:

[R0Wi]

@susnux may I kindly ask you for a review, please?

[R0Wi]

@nextcloud/server-frontend anyone who could give me feedback, please?

[R0Wi]

@come-nc the failing cypress tests seem to be unrelated? AFAIK there are no workflowengine E2E tests ...