Bump karaf to 4.2.5

Bump karaf to 4.2.5

This bumps karaf to 4.2.5, removing some workarounds we had to put
in place.

Notable upgrade is javax.annotation-api going from 1.2 to 1.3,
full release notes are here:

https://issues.apache.org/jira/secure/ReleaseNote.jspa?projectId=12311140&version=12344587
https://issues.apache.org/jira/secure/ReleaseNote.jspa?projectId=12311140&version=12344856
https://issues.apache.org/jira/secure/ReleaseNote.jspa?projectId=12311140&version=12345153

We also fix https://issues.apache.org/jira/browse/KARAF-6259 by
manually downgrading Equinox.

Change-Id: If9719909389df5c0b92c9aade0356d4a314ff756
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit 2e35dfeaaf555598bbf10b00cc046e7a198d081b)