Fix score conversion incorrectly assuming zero combo score in certain cases

[bdach]

This fell out during work on #26405.

Turns out the assumption of "if combo score plus bonus score is zero then relax / autopilot must have been on" from #26082 is overreaching. https://osu.ppy.sh/beatmapsets/675779#osu/1431549 is a beatmap which has a difficultyPeppyStars of zero (0), which means that it doesn't get any combo score (and also happens to have no bonus score), which means that going by

osu/osu.Game/Rulesets/Scoring/ScoreProcessor.cs

Line 369 in 70ba5dd

double comboProgress = maximumComboPortion > 0 ? currentComboPortion / maximumComboPortion : 1;

there's not really anything smart to do other than give it the full combo portion of score for free. And yes this probably helps some bad scores too much, but also makes SSes actually worth 960k score rather than 96% of accuracy portion.

This affects all rulesets, but judging from the osu! spreadsheet that I ran (https://docs.google.com/spreadsheets/d/1PmtF9maLl2WAc9BGDx02yv_YqU-2N9wftr0JOZk0m_k/edit#gid=469242467), there is only one beatmap affected by this.

I intentionally am not bumping LegacyScoreEncoder.LATEST_VERSION because I already have 2 other pulls open that touch it. It'll fall in there too is what I'm thinking.