Detect startup failures in additional Tomcat connectors

Previously, only the state of the primary connector was checked when
verifying that the embedded Tomcat instance has started successfully.
This commit updates the verification logic to examine all of the
service's connectors, thereby also detecting startup failures of any
additional connectors the have been configured.

A check on the primary connector's state has been removed from
initialize as, at this stage, its state will always be NEW.

Fixes gh-1591