storage: Don't pass a context into background tasks
storage: Don't pass a context into background tasks

Now that this context contains a tracer, this will panic if if the
background tasks ever have to log.

Fixes #8732

petermattis/cockroach,cockroachdb/cockroach,glycerine/cockroach,petermattis/cockroach,paperstreet/cockroach,cockroachdb/cockroach,veteranlu/cockroach,maxlang/cockroach,maxlang/cockroach,veteranlu/cockroach,petermattis/cockroach,vaibhavarora/cockroach,vaibhavarora/cockroach,vaibhavarora/cockroach,glycerine/cockroach,cockroachdb/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,cockroachdb/cockroach,maxlang/cockroach,paperstreet/cockroach,cockroachdb/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,petermattis/cockroach,maxlang/cockroach,cockroachdb/cockroach,glycerine/cockroach,maxlang/cockroach,glycerine/cockroach,paperstreet/cockroach,glycerine/cockroach,glycerine/cockroach,petermattis/cockroach,paperstreet/cockroach,paperstreet/cockroach,vaibhavarora/cockroach,maxlang/cockroach,glycerine/cockroach,veteranlu/cockroach,petermattis/cockroach,veteranlu/cockroach,petermattis/cockroach,cockroachdb/cockroach,maxlang/cockroach,glycerine/cockroach,petermattis/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,maxlang/cockroach,veteranlu/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach