Adapt to the latest changes on Gerrit master

Gerrit master introduced a new project cache that
requires the its-jira integration tests to be amended
to stop mutating the project cache directly.

And upstep wiremock to java 11 compatible version.

Co-authored-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: Steven Aerts <steven.aerts@gmail.com>
Change-Id: I57b78cefed1004263bec20418cc86e67466259a3