Temporary, backportable fix for -fno-code memory leaks (#20509)
As observed in #20509 there was a problem with a backpack hack which caused potential for large amounts of memory to be retained in interactive sessions when using -fno-code.
This "fix" just makes sure the hack is applied in less situations. If you are using backpack then you are still susceptible to these kinds of leaks but given that backpack barely works with GHCi anyway, it's not critical.