Remove unneeded workaround for IBM JDK and older intellij-core

The underlying problem (IDEA-206446) was fixed a long time ago and the
compiler is no longer affected by it.

 #KT-37286 Fixed

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt

@@ -517,8 +517,6 @@ class KotlinCoreEnvironment private constructor(
         }
 
         private fun registerApplicationExtensionPointsAndExtensionsFrom(configuration: CompilerConfiguration, configFilePath: String) {
-            workaroundIbmJdkStaxReportCdataEventIssue()
-
             fun File.hasConfigFile(configFile: String): Boolean =
                 if (isDirectory) File(this, "META-INF" + File.separator + configFile).exists()
                 else try {
@@ -542,38 +540,6 @@ class KotlinCoreEnvironment private constructor(
             registerExtensionPointAndExtensionsEx(pluginRoot, configFilePath, Extensions.getRootArea())
         }
 
-        private fun workaroundIbmJdkStaxReportCdataEventIssue() {
-            if (!SystemInfo.isIbmJvm) return
-
-            // On IBM JDK, XMLInputFactory does not support "report-cdata-event" property, but JDOMUtil sets it unconditionally in the
-            // static XML_INPUT_FACTORY field and fails with an exception (Logger.error throws exception in the compiler) if unsuccessful.
-            // Until this is fixed in the platform, we workaround the issue by setting that field to a value that does not attempt
-            // to set the unsupported property.
-            // See IDEA-206446 for more information
-            val field = JDOMUtil::class.java.getDeclaredField("XML_INPUT_FACTORY")
-            field.isAccessible = true
-            Field::class.java.getDeclaredField("modifiers")
-                .apply { isAccessible = true }
-                .setInt(field, field.modifiers and Modifier.FINAL.inv())
-            field.set(null, object : NotNullLazyValue<XMLInputFactory>() {
-                override fun compute(): XMLInputFactory {
-                    val factory: XMLInputFactory = try {
-                        // otherwise wst can be used (in tests/dev run)
-                        val clazz = Class.forName("com.sun.xml.internal.stream.XMLInputFactoryImpl")
-                        clazz.newInstance() as XMLInputFactory
-                    } catch (e: Exception) {
-                        // ok, use random
-                        XMLInputFactory.newFactory()
-                    }
-
-                    factory.setProperty(XMLInputFactory.IS_COALESCING, true)
-                    factory.setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false)
-                    factory.setProperty(XMLInputFactory.SUPPORT_DTD, false)
-                    return factory
-                }
-            })
-        }
-
         @JvmStatic
         @Suppress("MemberVisibilityCanPrivate") // made public for CLI Android Lint
         fun registerPluginExtensionPoints(project: MockProject) {