chore: check integrationStatus before trying to use calendar

[gikf]

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• My pull request has a descriptive title (not a vague title like Update README.md).
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• Adds check of the integrationStatus before using calendar.
• Change isn't that big as it might look like, external api wouldn't be actually used anyway, but I find more sensible to do the check first, instead of letting the service call error.

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[ojeytonwilliams]

Thanks, @gikf, I think it makes sense to put the burden on our db rather than sending requests to Google that we know will fail.

LGTM 👍