NXCALS-2511 Optional SSL trustStore definition

#Merge request template @acc-logging-team - please have a look for approval.

This MR changes the SSL trustStore loading strategy to state in optional for the end user of NXCALS.

If the user hasn't specified any system properties for SSL trustStore loading, then the static configuration in the service-client "kicks-in" and defines the needed system properties to point on the internally versioned trustStore file. This file contains the needed CA grid certificates in order to allow the client to submit HTTPS requests against our services.

Closes NXCALS-2511