[I/Y-Build] Unify index.template.php site for I and Y builds

The existing differences are not relevant and probably only due to
omitted synchronization.
For the 'dropTemplateFileName' property, rely on the default, which is
exactly the new unify filename.

Part of #2625

cje-production/mbscripts/mb300_gatherEclipseParts.sh

@@ -256,7 +256,6 @@ $JavaCMD -jar $LAUNCHER_JAR \
   -DpostingDirectory=$CJE_ROOT/$DROP_DIR \
   -DequinoxPostingDirectory=$BUILD_ROOT/$EQUINOX_DROP_DIR \
   -DpublishingContent=$ECLIPSE_BUILDER_DIR/eclipse/publishingFiles \
-  -DdropTemplateFileName=$ECLIPSE_BUILDER_DIR/eclipse/publishingFiles/templateFiles/index.template_$PATCH_OR_BRANCH_LABEL.php \
   -DindexFileName=index.php \
   -DeclipseStream=$STREAM \
   -Dbase.builder=$CJE_ROOT/$BASEBUILDER_DIR \

cje-production/mbscripts/mb310_gatherEquinoxParts.sh

@@ -83,7 +83,6 @@ ${JAVA_HOME}/bin/java -jar $LAUNCHER_JAR \
   -DpostingDirectory=$CJE_ROOT/$DROP_DIR/$BUILD_ID \
   -DequinoxPostingDirectory=$CJE_ROOT/$EQUINOX_DROP_DIR \
   -DeqpublishingContent=$ECLIPSE_BUILDER_DIR/equinox/publishingFiles \
-  -DdropTemplateFileName=$ECLIPSE_BUILDER_DIR/eclipse/publishingFiles/templateFiles/index.template_$PATCH_OR_BRANCH_LABEL.php \
   -DindexFileName=index.php \
   -DeclipseStream=$STREAM \
   -Dequinox.build.configs=$ECLIPSE_BUILDER_DIR/equinox/buildConfigs \

cje-production/scripts/genTestIndexes.xml

@@ -95,7 +95,6 @@
     <!-- These variables used to be defined here, but now are defined in 
          publish.xml generateIndex target based on $job
       indexFileName
-      dropTemplateFileName
       testManifestFileName
     -->