Fix unhandled exception test for composite r2r case (#109244)

The test fails when built as r2r composite on linux coreclr due to the fact that the
unhandled exception differs in this case from regular non-composite or non-r2r builds.
It gets System.EntryPointNotFoundException instead of System.DllNotFoundException due
to a different order the resolving happens in this case.

This change fixes that by modifying the unhandledTester to accept both of these
cases as success.

Author: janvorli

src/tests/baseservices/exceptions/unhandled/unhandledTester.cs

@@ -98,7 +98,8 @@ static void RunExternalProcess(string unhandledType, string assembly)
                 }
                 else if (unhandledType == "foreign")
                 {
-                    if (!lines[0].StartsWith("Unhandled exception. System.DllNotFoundException:"))
+                    if (!lines[0].StartsWith("Unhandled exception. System.DllNotFoundException:") &&
+                        !lines[0].StartsWith("Unhandled exception. System.EntryPointNotFoundException: Unable to find an entry point named 'HelloCpp'"))
                     {
                         throw new Exception("Missing Unhandled exception header");
                     }