Standardize osu!catch coordinate system

There were two coordinate systems used:
- 0..512 (used in osu!stable)
- 0..1 (relative coordinate)

This commit replaces the usage of
the relative coordinate system to
the coordinate system of 0..512.

osu.Game.Rulesets.Catch.Tests/TestSceneCatcherArea.cs

@@ -76,8 +76,8 @@ namespace osu.Game.Rulesets.Catch.Tests
                 RelativeSizeAxes = Axes.Both,
                 Child = new TestCatcherArea(new BeatmapDifficulty { CircleSize = size })
                 {
-                    Anchor = Anchor.CentreLeft,
-                    Origin = Anchor.TopLeft,
+                    Anchor = Anchor.Centre,
+                    Origin = Anchor.TopCentre,
                     CreateDrawableRepresentation = ((DrawableRuleset<CatchHitObject>)catchRuleset.CreateInstance().CreateDrawableRulesetWith(new CatchBeatmap())).CreateDrawableRepresentation
                 },
             });