Update self-managed phrasing in CI docs

doc/administration/settings/continuous_integration.md

doc/ci/components/index.md

doc/ci/debugging.md

doc/ci/index.md

doc/ci/jobs/ci_job_token.md

doc/ci/jobs/job_artifacts.md

doc/ci/migration/bamboo.md

doc/ci/migration/jenkins.md

doc/ci/pipelines/compute_minutes.md

doc/ci/pipelines/index.md

doc/ci/runners/runners_scope.md

doc/ci/testing/code_quality_codeclimate_scanning.md

doc/ci/variables/index.md

doc/ci/yaml/artifacts_reports.md

doc/ci/yaml/includes.md

doc/ci/yaml/index.md