Stop publishing the obsolete org.eclipse.equinox.executable unit

This unit is now effectively only an alias for the
'org.eclipse.equinox.executable.feature.group' unit. If any reference to
the former still exists, it should be changed to use the latter instead.

Follow-up on
- eclipse-equinox/equinox#1089

Author: HannesWell

eclipse.platform.releng.tychoeclipsebuilder/eclipse.platform.repository/category.xml

@@ -46,11 +46,6 @@
    <iu id = "org.eclipse.platform.ide">
      <category name="org.eclipse.platform.ide.categoryIU"/>
    </iu>
-   <iu>
-     <query> 
-       <expression type="match">id == 'org.eclipse.equinox.executable'</expression>
-     </query>
-   </iu>
    <category-def name="org.eclipse.equinox.target.categoryIU" label="Equinox Target Components">
       <description>
          Features especially useful to install as PDE runtime targets.

eclipse.platform.releng.tychoeclipsebuilder/equinox/buildConfigs/equinox-launchers/build.xml

@@ -39,7 +39,6 @@
         <destination kind="metadata" location="file://${featureTemp}" name="Equinox Launchers Repo" format="file://${buildRepo}" />
         <destination kind="artifact" location="file://${featureTemp}" name="Equinox Launchers Repo" format="file://${buildRepo}" />
         <iu id="org.eclipse.equinox.executable.feature.group" version="" />
-        <iu id="org.eclipse.equinox.executable" version="" />
         <slicingOptions platformFilter="@{os},@{ws},@{arch}" includeOptional="false" includeNonGreedy="false" followStrict="true" />
       </p2.mirror>
       <p2.repo2runnable destination="${featureTemp2}/eclipse">