Add org.eclipse.core.tools to org.eclipse.releng.testsIU

- This is the category labeled `Eclipse Tests, Tools, Examples, and
Extras`  with description `Collection of Misc. Features, such as unit
tests, SWT and e4 tools, examples, and compatibility features not
shipped as part of main SDK, but which some people may desire in
creating products based on previous versions of Eclipse.`.

eclipse-platform/eclipse.platform#2457

Author: merks

sites/eclipse-platform-repository/category.xml

@@ -36,6 +36,9 @@
       <category name="org.eclipse.releng.pde.categoryIU"/>
    </feature>
    <feature id="org.eclipse.pde.osgitest.dependencies.feature"/>
+   <feature id="org.eclipse.core.tools">
+      <category name="org.eclipse.releng.testsIU"/>
+   </feature>
    <bundle id="jakarta.annotation-api" version="1.3.5"/>
    <bundle id="jakarta.inject.jakarta.inject-api" version="1.0.5"/>
    <bundle id="org.eclipse.equinox.slf4j"/>