This reverts commit f3faad74d5, reversing
changes made to 712e7bc7bf.
Several issues arose after migrating to 5.0, including, but possibly not
limited to, performance regressions in song select, as well as failures
when attempting to save beatmaps after metadata changes in the editor.
Some .osu file sources (or database sources) may be in a bad state. We want to get these ones right as they cannot be enforced by the database itself (via FKs or constraints).
There is now a CreateContext method for retrieving a stand-alone context for threaded use.
We may want to add safety against this context being disposed (or just return a fresh one if it is).