Stop marking scores as ranked = 0 for pp only purposes

[peppy]

We use this flag for cases where scores should not be considered for PP or leaderboards now. Cases where PP is not required simply leaves it as null.

[bdach]

Cases where PP is not required simply leaves it as null.

I assume this is going to regress the pp display fix made at ppy/osu-web#10918 / ppy/osu#27053 for scores set e.g. on unranked mods? cc @ppy/team-web

I'm not sure how to fix either because both "pp pending calculation" and "pp is just not given for this score" are indistinguishable. Unless you check the process history entry maybe.

[peppy]

Yeah, good call there. We'll either need to have local logic to check the conditions for whether a score should award PP, or come up with another value to represent what we were using null for..

I guess using the process_history could work, although I'm not confident we'll be keeping that table around.