Consider supporting optional old runs deletion

[nokernel]

After a while old Terraform runs output are no longer relevant.

Consider purging them from the DB could help on OTF env where quite a few Terraform apply|plans are getting executed.

A optional configuration with variable time could be something that would help lower the stress on DB and help speed up web interface etc etc.

[danielaraujobc]

+1 for that. The old runs consume a lot of database storage (in my scenario) compared to other resources. It would be beneficial to allow deletion or to set a retention period.

[leg100]

I think both are approaches are quite viable. I'll get on it.