Preinstall javax.servlet-api to standalone-container.
It's currently needed by vespa-athenz, which is installed in
all containers, except metrics-proxy and clustercontroller.
<!-- START bundles that can be moved to config-model when all standalone containers are set up via the model -->
container-spifly.jar, <!-- Aries SPIFly repackaged -->
+ javax.servlet-api-3.1.0.jar, <!-- Needed by vespa-athenz. TODO Vespa 9: remove the need for servlet-api -->
<!-- END bundles that can be moved to config-model -->
<!-- START config-model dependencies -->
