Clean up airflow scheduler

[irainia]

Description
This is part of this discussion. There are some todos in airflow scheduler implmentations. This issue is to address such todos:

• method ListJobs can get record from db
• todo that mentions about removing project spec in airflow2/client.go

Tech Details

• on the second point about removing project spec, we need to pass only the required arguments

[sbchaos]

We have addressed other todos. For getting records from db, it will take some time, db does not have enough records to replace airflow as source of truth.