All jobs in periodic pipeline failing to report to dlrn due to missing credentials

logs at

https://logs.rdoproject.org/openstack-periodic/git.openstack.org/openstack-infra/tripleo-ci/master/periodic-tripleo-ci-centos-7-ovb-1ctlr_1comp-featureset002-master-upload/7dc4975/job-output.txt.gz#_2019-03-04_11_51_08_643631

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2019-03-04 11:51:08.643631 | primary | + dlrnapi --url https://trunk.rdoproject.org/api-centos-master-uc report-result --commit-hash d801d48492823347a8f8ee64ded82a82eef9911a --distro-hash 01511b06a16589ec359b62a6cb5461686e680a66 --job-id periodic-tripleo-ci-centos-7-ovb-1ctlr_1comp-featureset002-master-upload --info-url https://logs.rdoproject.org/openstack-periodic/git.openstack.org/openstack-infra/tripleo-ci/master/periodic-tripleo-ci-centos-7-ovb-1ctlr_1comp-featureset002-master-upload/7dc4975 --timestamp 1551700268 --success False
2019-03-04 11:51:08.709618 | primary | Traceback (most recent call last):
2019-03-04 11:51:08.709742 | primary | File "/usr/bin/dlrnapi", line 10, in <module>
2019-03-04 11:51:08.709786 | primary | sys.exit(main())
2019-03-04 11:51:08.709908 | primary | File "/usr/lib/python2.7/site-packages/dlrnapi_client/shell.py", line 342, in main
2019-03-04 11:51:08.709954 | primary | if e.status == 404:
2019-03-04 11:51:08.710082 | primary | AttributeError: 'exceptions.TypeError' object has no attribute 'status'

Investigation on dlrnapi client and server showed that the client doens't handle an error condition properly, but the initial condition itself is caused by missing credentials.
Dlrnapi developer are rectifying the problems there, but we are still broken

Probaly
https://review.rdoproject.org/r/19064
caused the error.

The change is removing the username from the reporting, in preparation for the migration to a new role that is not ready yet.