Use GX_CMD_UNKNOWN_METRICS instead of magic number 0x44

[Pokechu22]

Defined to be 0x44 here:

dolphin/Source/Core/VideoCommon/OpcodeDecoding.h

Line 30 in 79a234e

GX_CMD_UNKNOWN_METRICS = 0x44,

and already used in OpcodeDecoding here:

dolphin/Source/Core/VideoCommon/OpcodeDecoding.cpp

Lines 202 to 206 in 79a234e

	case GX_CMD_UNKNOWN_METRICS: // zelda 4 swords calls it and checks the metrics registers after
	// that
	total_cycles += 6;
	DEBUG_LOG_FMT(VIDEO, "GX 0x44: {:08x}", cmd_byte);
	break;

That log message also has a 0x44 in it, but since it seems like the exact purpose of this command is unknown, I think it's fine to leave it like that. On the other hand, the code uses in both FifoAnalyzer.cpps are a situation where we want 0x44 to match the name, especially if the name is later changed.