Remove Crossgen2's -O option in Test Builds Wherever Possible (#89223)

* Removed the Crossgen2 -O option from CLRTest.CrossGen.targets file.

* Removed the remaining Crossgen2-related -O's I could find. Not sure if
all of them should be removed though.

* Restored the ReadyToRunCompiler -O option because some NativeAOT tests
apparently are not happy without it.

* Restored crossgen-corelib.proj's -O because extra-platforms is still complaining.

* Restored the -O in a python script to see if Mono stops being an
annoying pain.

* Restored even the original change just to see whether there is
actually a problem with the extra-platforms, or they're just trolling
at this point.

* Removed the -O's from Crossgen2 again after discovering the
extra-platforms pipelines are super broken right now.

Author: ivdiazsa

src/coreclr/crossgen-corelib.proj

@@ -127,7 +127,6 @@
       <CrossGenDllCmd>$(CrossGenDllCmd) --targetarch:$(TargetArchitecture)</CrossGenDllCmd>
       <CrossGenDllCmd>$(CrossGenDllCmd) --targetos:$(TargetOS)</CrossGenDllCmd>
       <CrossGenDllCmd Condition="'$(UsingToolIbcOptimization)' != 'true' and '$(EnableNgenOptimization)' == 'true'">$(CrossGenDllCmd) -m:$(MergedMibcPath) --embed-pgo-data</CrossGenDllCmd>
-      <CrossGenDllCmd>$(CrossGenDllCmd) -O</CrossGenDllCmd>
       <CrossGenDllCmd  Condition="'$(Configuration)' == 'Debug' or '$(Configuration)' == 'Checked'">$(CrossGenDllCmd) --verify-type-and-field-layout</CrossGenDllCmd>
       <CrossGenDllCmd>$(CrossGenDllCmd) @(CoreLib)</CrossGenDllCmd>
     </PropertyGroup>

src/tests/Common/CLRTest.CrossGen.targets

@@ -1,6 +1,6 @@
 <!--
 ***********************************************************************************************
-CLRTest.Execute.targets
+CLRTest.CrossGen.targets
 
 WARNING:  DO NOT MODIFY this file unless you are knowledgeable about MSBuild and have
           created a backup copy.  Incorrect changes to this file will make it
@@ -113,7 +113,6 @@ if [ ! -z ${RunCrossGen2+x} ]%3B then
         fi
         echo --targetarch:$(TargetArchitecture)>>$__ResponseFile
         echo --targetos:$(TargetOS)>>$__ResponseFile
-        echo -O>>$__ResponseFile
 
         echo "Response file: $__ResponseFile"
         cat $__ResponseFile
@@ -263,7 +262,6 @@ if defined RunCrossGen2 (
     echo -r:!CORE_ROOT!\xunit.*.dll>>!__ResponseFile!
     echo -r:!CORE_ROOT!\mscorlib.dll>>!__ResponseFile!
     echo -r:!CORE_ROOT!\netstandard.dll>>!__ResponseFile!
-    echo -O>>!__ResponseFile!
 
     if not "$(__CreatePdb)" == "" (
         echo --pdb>>!__ResponseFile!