test(nes): consolidate and simplify inline subsystem unit tests

src/system/nes/mapper/mmc4.zig

@@ -2,7 +2,7 @@ const std = @import("std");
 const common = @import("../common.zig");
 const Mirroring = common.Mirroring;
 
-// ponytail: Mapper 10 (MMC4) - Fire Emblem & Fire Emblem Gaiden
+// Mapper 10 (MMC4) - Fire Emblem & Fire Emblem Gaiden
 // 16KB switchable PRG at $8000, fixed last 16KB at $C000-$FFFF.
 // Dual 4KB CHR latches toggled by PPU fetches at $xFD8-$xFDF and $xFE8-$xFEF.
 pub const Mmc4 = @This();