Lot of jobs do not discard their build history which is filling up the disk on gallium (T91211). Most of the jobs should have a day based logrotation ie in jjb:
```
lang=yaml
logrotate:
daysToKeep: 30
```
Example of top offenders:
```
cd /var/lib/jenkins/jobs
$ stat --format '%h:%n' */builds|sort -rn|head -n30
13371:operations-puppet-tox-data_admin_lint/builds
12284:mwext-Wikibase-lint/builds
10051:mwext-MobileFrontend-lint/builds
8989:mwext-MobileFrontend-qunit/builds
8983:mwext-MobileFrontend-qunit-mobile/builds
8821:mwext-Flow-lint/builds
8713:operations-apache-config-lint/builds
7512:mwext-VisualEditor-lint/builds
7003:mwext-VisualEditor-npm/builds
7002:mwext-VisualEditor-qunit/builds
6991:mwext-VisualEditor-doc-test/builds
6932:operations-mw-config-tests/builds
5672:mwext-Wikibase-qunit/builds
5656:mwext-Wikibase-repo-tests/builds
5653:mwext-Wikibase-repo-api-tests/builds
5642:mwext-Wikibase-client-tests/builds
5618:mediawiki-core-doxygen-publish/builds
5463:mediawiki-gate/builds
5353:VisualEditor-npm/builds
5096:pywikibot-core-tox-flake8/builds
5040:mediawiki-core-phplint/builds
4863:operations-puppet-validate/builds
4777:VisualEditor-jsduck/builds
4638:mediawiki-core-bundle-rubocop/builds
4422:mwext-Flow-qunit/builds
4384:mwext-MobileFrontend-phpcs-HEAD/builds
4263:mediawiki-core-regression-phpcs-HEAD/builds
3953:pywikibot-core-tox-nose/builds
3920:mwext-MobileFrontend-jslint/builds
3808:operations-puppet-puppetlint-strict/builds
```