Narrow disassembly IR selection to ARM64

Agent-Logs-Url: https://github.com/microsoft/profile-explorer/sessions/73d867c4-8362-43ed-ab4f-a1772c3f20c6

Co-authored-by: jhpohovey <42473764+jhpohovey@users.noreply.github.com>

Author: Copilot

src/ProfileExplorerCore/Compilers/ASM/DisassemblerSectionLoader.cs

@@ -43,7 +43,6 @@ private static ICompilerIRInfo SelectIRInfo(ICompilerInfoProvider compilerInfo,
 
     return binaryInfo?.Architecture switch {
       Machine.Arm64 => new ASMCompilerIRInfo(IRMode.ARM64),
-      Machine.Arm   => new ASMCompilerIRInfo(IRMode.ARM64),
       Machine.I386  => new ASMCompilerIRInfo(IRMode.x86_64),
       Machine.Amd64 => new ASMCompilerIRInfo(IRMode.x86_64),
       _             => compilerInfo.IR