Changed the start script name in cinder-volume

In the Dockerfile of cinder-volume, the "kolla_extend_start" script
will be overwritten, and it will cause the cinder-volume container
doesn't create /var/log/kolla/cinder folder.
The name of the start script should be "kolla_cinder_extend_start" in
cinder-volume container.

Change-Id: I7251792a4fbe1442e2ffc5ebd9e41bd9cdc33568
Closes-Bug: #1638839

docker/cinder/cinder-volume/Dockerfile.j2

@@ -44,11 +44,11 @@ RUN sed -i '1 i include /var/lib/cinder/volumes/*' /etc/tgt/targets.conf
 {% endif %}
 
 COPY cinder_sudoers /etc/sudoers.d/cinder_sudoers
-COPY extend_start.sh /usr/local/bin/kolla_extend_start
+COPY extend_start.sh /usr/local/bin/kolla_cinder_extend_start
 
 RUN chmod 750 /etc/sudoers.d \
     && chmod 440 /etc/sudoers.d/cinder_sudoers \
-    && chmod 755 /usr/local/bin/kolla_extend_start
+    && chmod 755 /usr/local/bin/kolla_cinder_extend_start
 
 {% block cinder_volume_footer %}{% endblock %}
 {% block footer %}{% endblock %}