Adjust relax mod multiplayer to 0.5x

Has previously been discussed internally. Probably good to get this out
before the next full reprocess of scores server-side.

The multiplier here was @smoogipoo's suggested value. I'd be willing to
go lower if this is seen at too high, but it should be a round number to
make it easy for users to understand the max score available to them.

osu.Game/Rulesets/Mods/ModRelax.cs

@@ -13,7 +13,7 @@ namespace osu.Game.Rulesets.Mods
         public override string Acronym => "RX";
         public override IconUsage? Icon => OsuIcon.ModRelax;
         public override ModType Type => ModType.Automation;
-        public override double ScoreMultiplier => 1;
+        public override double ScoreMultiplier => 0.5;
         public override Type[] IncompatibleMods => new[] { typeof(ModAutoplay), typeof(ModNoFail), typeof(ModFailCondition) };
     }
 }