Revert "Ensure using the given executable path. (dotnet/coreclr#10525)…

…" (dotnet#31848)

Reverts dotnet/coreclr#10525.

This broke probing for .ni.exe images. If we run `corerun foo.exe` for something that has a `foo.ni.exe`, we wouldn't pick up the native image because foo.exe is considered trusted and foo.ni.exe is not. This means we would fall back to JIT. But only if foo.exe is not in CORE_ROOT. If it is, it works...

The pull request broke crossgen testing that was eventually worked around in dotnet/coreclr#11272, but it's also breaking the tests in tests\src\readytorun\tests (we just didn't find out because they're falling back to JIT). We could work around there too, but this took half a day for me to investigate, so I don't want to leave the landmine there for someone else to lose a leg over (the fact that ni probing works if you put the exe and ni.exe into CORE_ROOT was a major timesink when troubleshooting).

I don't see much point in this change. It's fixing the case when someone copied something.exe to CORE_ROOT and then tries to `corerun some\other\version\of\something.exe`, but it doesn't fix the situation when the something.exe depends on dependency.dll - we would still pick up dependency.dll from CORE_ROOT, which is likely the wrong version. The only way to win this game is not to play it - don't put stuff in CORE_ROOT.

src/coreclr/src/hosts/corerun/corerun.cpp

@@ -582,18 +582,6 @@ bool TryRun(const int argc, const wchar_t* argv[], Logger &log, const bool verbo
         return false;
     }
 
-    StackSString tpaList;
-    if (!managedAssemblyFullName.IsEmpty())
-    {
-        // Target assembly should be added to the tpa list. Otherwise corerun.exe
-        // may find wrong assembly to execute.
-        // Details can be found at https://github.com/dotnet/coreclr/issues/5631
-        tpaList = managedAssemblyFullName;
-        tpaList.Append(W(';'));
-    }
-
-    tpaList.Append(hostEnvironment.GetTpaList());
-
     //-------------------------------------------------------------
 
     // Create an AppDomain
@@ -623,7 +611,7 @@ bool TryRun(const int argc, const wchar_t* argv[], Logger &log, const bool verbo
     };
     const wchar_t *property_values[] = {
         // TRUSTED_PLATFORM_ASSEMBLIES
-        tpaList,
+        hostEnvironment.GetTpaList(),
         // APP_PATHS
         appPath,
         // APP_NI_PATHS

src/coreclr/src/hosts/unixcoreruncommon/coreruncommon.cpp

@@ -350,15 +350,6 @@ int ExecuteManagedAssembly(
     GetDirectory(managedAssemblyAbsolutePath, appPath);
 
     std::string tpaList;
-    if (strlen(managedAssemblyAbsolutePath) > 0)
-    {
-        // Target assembly should be added to the tpa list. Otherwise corerun.exe
-        // may find wrong assembly to execute.
-        // Details can be found at https://github.com/dotnet/coreclr/issues/5631
-        tpaList = managedAssemblyAbsolutePath;
-        tpaList.append(":");
-    }
-
     // Construct native search directory paths
     std::string nativeDllSearchDirs(appPath);
     char *coreLibraries = getenv("CORE_LIBRARIES");
@@ -371,7 +362,6 @@ int ExecuteManagedAssembly(
             AddFilesFromDirectoryToTpaList(coreLibraries, tpaList);
         }
     }
-
     nativeDllSearchDirs.append(":");
     nativeDllSearchDirs.append(clrFilesAbsolutePath);