gRPC user needs to be in EOS +sudo group

castor-dbtools is required by cta-migration-tools

Added activable logs to the RetrieveQueueStatistics cache for debugging

An example value of sys.retrieve.error is as follows:

[itctabuild02] ~ > sudo eos attr ls /eos/dev/userfiles/testdir_1/test_1 | grep sys.retrieve.error
sys.retrieve.error="Garbage collected at 2019/09/09 16:27:26.609570"
[itctabuild02] ~ >

This can now be done without tearing down and re-creating the containers.

Added error messages in case of problems for easier diagnosis.

Conflicts:
	continuousintegration/docker/ctafrontend/cc7/opt/run/bin/ctaeos-mgm.sh

Conflicts:
	continuousintegration/orchestration/tests/repack_systemtest_wrapper.sh

Added report generation to repack_generate_report.sh so that it honours the repack "add copies only" and the repack "Move and add copies"