Refactor initialization of Instance Id Manager

    /**
     * Used to initialize the unique XWiki instance id (to be removed in the future, see the source documentation
     * below).
     * <p>
     * Note that we use a Provider since the Observation Manager will register listeners very early in the
     * initialization process and some of the components injected transitively by the {@link InstanceIdManager}
     * implementation have initialization code that require an Execution Context to be available, which is not the case
     * early one in XWiki's initialization since no HTTP request has been made yet...
     */
    @Inject
    private Provider<InstanceIdManager> instanceIdManagerProvider;

        // Ensure that the instance id is initialized and available.
        // TODO: In the future introduce an EventListener in the instance module and have this listener execute *after*
        this.instanceIdManagerProvider.get().initializeInstanceId();