AIP-44 Remove job_runner from BaseJob as a final step of decoupling

[potiuk]

As discussed in #30255 (comment) and #30255 (comment) - I think eventually (after #30308 especially, we should be able to get rid of the job_runner back-reference to the job_runner in the BaseJob - this will simplify the relation.

It will be easier however to do it in those steps we have now (each of those changes is relatively small (in terms of base code) and separately reviewable - and we can make sure Airlfow continues to work after each of those steps which makes it easier to implement and merge those changes faster):

#30255 -> #30302 -> #30308 -> this one

CC: @uranusjr @mhenc