releng: Add profile to disable jacoco

releng: Add profile to disable jacoco

So that we can disable it for the Gerrit trigger and make it a bit
faster, hopefully. To disable it use
mvn clean install -Dskip-jacoco=true

Change-Id: I5ab53302df910ddeac1d2fa4afa2f2c020c85ff3
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/65235
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-by: Hudson CI