Add trigger as a valid option for the db clean command

[syedahsn]

closes: #34906
This is a potential solution to the issue mentioned above. There is an existing command, airflow db clean that removes old records from the DB. This command currently does not support the triggers table, so it cannot be used. This PR solves the issue linked above by allowing the user to manually delete outdated records in the triggers table, which also removes the notification about the Trigger not being active.

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[syedahsn]

@dstandish do you mind taking a look at this issue? I'm wondering if this is the best way to solve the problem.

[dstandish]

Why do we need to clear the record?

[dstandish]

I don't see a problem with this. But seems quite rare that anyone would need it.