Remove the legacy ARM32 JIT

The IR-based one replaces it. With that, every native JIT is IR-based, which the JIT viewer and
the settings' comments now assume. The ARM emitter test loses its part that drove the old FPU
register cache.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Core/Config.cpp

@@ -1587,8 +1587,8 @@ bool Config::Save(const char *saveReason) {
 
 // A lot more cleanup tasks should be moved into here, and some of these are severely outdated.
 void Config::PostLoadCleanup() {
-	// JIT_IR is the same core as JIT now that the legacy x86 and ARM64 JITs are gone, and the
-	// settings no longer offer it.
+	// JIT_IR is the same core as JIT now that every native JIT is IR-based, and the settings no
+	// longer offer it.
 	if (iCpuCore == (int)CPUCore::JIT_IR) {
 		iCpuCore = (int)CPUCore::JIT;
 	}