Replace label on refactored MQTT option flow button

[jbouwh]

Proposed change

The MQTT option flow is to be refactored with home-assistant/core#133342. The option flow no longer supportes a full reconfiguration.

This PR replaces the label on the MQTT OptionFlow button.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to core PR: Refactor the MQTT option and reconfigure flow core#133342
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[MindFreeze]

Should we merge this now? I think this label works even without the refactor