Remove PAL oleauto.h shim and stale CoreCLR includes (#129874)

`src/coreclr/pal/inc/rt/oleauto.h` was a PAL-era shim that is no longer
needed for current CoreCLR builds.

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

Author: Copilot

src/coreclr/inc/utilcode.h

@@ -22,7 +22,6 @@ using std::nothrow;
 #include "winwrap.h"
 #include <wchar.h>
 #include <ole2.h>
-#include <oleauto.h>
 #include "clrtypes.h"
 #include "safewrap.h"
 #include "volatile.h"

src/coreclr/pal/inc/rt/oleauto.h

@@ -8,10 +8,6 @@
 #include "cor.h"
 #include "corhlprpriv.h"
 
-#ifdef TARGET_UNIX
-#include <oleauto.h>
-#endif
-
 #define STRING_BUFFER_LEN 4096
 
 typedef void (*strPassBackFn)(const char *str);

src/coreclr/tools/metainfo/mdinfo.h

@@ -5,7 +5,6 @@
 #ifndef _COMDATETIME_H_
 #define _COMDATETIME_H_
 
-#include <oleauto.h>
 #include "fcall.h"
 
 #include <pshpack1.h>