Revert "[lldb] Set default object format to MachO in ObjectFileMachO (#142704)"

This reverts commit d4d2f069de.

Temporarily reverting until we can find a way to get the correct
ObjectFile set in Module's Triples without adding "-macho" to the
triple string for each Module.  This is breaking TestUniversal.py
on the x86_64 macOS CI bots.

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

@@ -5148,7 +5148,6 @@ void ObjectFileMachO::GetAllArchSpecs(const llvm::MachO::mach_header &header,
   llvm::Triple base_triple = base_arch.GetTriple();
   base_triple.setOS(llvm::Triple::UnknownOS);
   base_triple.setOSName(llvm::StringRef());
-  base_triple.setObjectFormat(llvm::Triple::MachO);
 
   if (header.filetype == MH_PRELOAD) {
     if (header.cputype == CPU_TYPE_ARM) {

lldb/unittests/ObjectFile/MachO/TestObjectFileMachO.cpp

@@ -94,59 +94,4 @@ TEST_F(ObjectFileMachOTest, IndirectSymbolsInTheSharedCache) {
   for (size_t i = 0; i < 10; i++)
     OF->ParseSymtab(symtab);
 }
-
-TEST_F(ObjectFileMachOTest, ObjectFormatWithoutVersionLoadCommand) {
-  // A Mach-O file without the load command LC_BUILD_VERSION.
-  const char *yamldata = R"(
---- !mach-o
-FileHeader:
-  magic:           0xFEEDFACF
-  cputype:         0x0100000C
-  cpusubtype:      0x00000000
-  filetype:        0x00000001
-  ncmds:           1
-  sizeofcmds:      152
-  flags:           0x00002000
-  reserved:        0x00000000
-LoadCommands:
-  - cmd:             LC_SEGMENT_64
-    cmdsize:         152
-    segname:         __TEXT
-    vmaddr:          0
-    vmsize:          4
-    fileoff:         184
-    filesize:        4
-    maxprot:         7
-    initprot:        7
-    nsects:          1
-    flags:           0
-    Sections:
-      - sectname:        __text
-        segname:         __TEXT
-        addr:            0x0000000000000000
-        content:         'AABBCCDD'
-        size:            4
-        offset:          184
-        align:           0
-        reloff:          0x00000000
-        nreloc:          0
-        flags:           0x80000400
-        reserved1:       0x00000000
-        reserved2:       0x00000000
-        reserved3:       0x00000000
-...
-)";
-
-  // Perform setup.
-  llvm::Expected<TestFile> file = TestFile::fromYaml(yamldata);
-  EXPECT_THAT_EXPECTED(file, llvm::Succeeded());
-  auto module_sp = std::make_shared<Module>(file->moduleSpec());
-  ASSERT_NE(module_sp, nullptr);
-  auto object_file = module_sp->GetObjectFile();
-  ASSERT_NE(object_file, nullptr);
-
-  // Verify that the object file is recognized as Mach-O.
-  ASSERT_EQ(object_file->GetArchitecture().GetTriple().getObjectFormat(),
-            llvm::Triple::MachO);
-}
 #endif