feat: support mysql backend as keda trigger

[claneys]

Closes: #36166

Airflow currently support two SQL database backend with postgresql and mysql. PostgreSQL being the default one it's also the trigger used by default by the Keda ScaledObject created when enabling autoscaling. Which do not work if using a mysql database. Query has to be changed a bit and mysql trigger parameters aren't the same (pretty sneaky little changes within key names) and most of all the connection string used isn't the correct one when addressing to mysql.

[boring-cyborg]

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[hussein-awala]

Could you add tests for mounted secret, kedaConnection value, and KEDA scaler when the protocol is MySQL?

[claneys]

Could you add tests for mounted secret, kedaConnection value, and KEDA scaler when the protocol is MySQL?

Yes, Sure :)

[claneys]

Hi @hussein-awala,

Happy new year :) Is the changes fine to you ? Thanks

[eladkal]

static checks are failing
@claneys can you fix it?

[claneys]

@eladkal Sure, I update the PR to make it pass.

[eladkal]

@claneys static tests are failing

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.