Remove invalid extensions from o.e.c.tests.runtime

The org.eclipse.core.tests.runtime plug-in contains invalid/unused
extensions and extension points. The class implementing the specified
extension does not exist, thus the extension is invalid and produces a
warning.

runtime/tests/org.eclipse.core.tests.runtime/plugin.xml

@@ -24,21 +24,4 @@
             class="org.eclipse.core.tests.internal.preferences.TestInitializer">
       </initializer>
    </extension>
-   <extension
-         point="org.eclipse.core.runtime.adapters">
-      <factory
-            class="org.eclipse.core.tests.runtime.TestAdapterFactory"
-            adaptableType="org.eclipse.core.tests.runtime.TestAdaptable">
-         <adapter
-               type="org.eclipse.core.tests.runtime.TestAdapter">
-         </adapter>
-      </factory>
-   </extension>
-   <extension-point id="factoryLoaderTest" name="factoryLoaderTest" schema="schema/factoryLoaderTest.exsd"/>
-   <extension point="org.eclipse.core.runtime.adapters">
-      <factory class="org.eclipse.core.tests.runtime.TestAdapterFactoryLoader" 
-         adaptableType="org.eclipse.core.tests.runtime.TestAdaptable">
-         <adapter type="testAdapter.testUnknown"/>
-      </factory>
-   </extension>
 </plugin>