Add CI_TEMPLATE_REGISTRY_HOST to predefined CI variables

lib/gitlab/ci/templates/Jobs/License-Scanning.gitlab-ci.yml

lib/gitlab/ci/templates/Jobs/SAST-IaC.gitlab-ci.yml

lib/gitlab/ci/templates/Jobs/SAST-IaC.latest.gitlab-ci.yml

lib/gitlab/ci/templates/Jobs/SAST.gitlab-ci.yml

lib/gitlab/ci/templates/Jobs/SAST.latest.gitlab-ci.yml

lib/gitlab/ci/templates/Jobs/Secret-Detection.gitlab-ci.yml

...b/ci/templates/Jobs/Secret-Detection.latest.gitlab-ci.yml

lib/gitlab/ci/templates/Pages/Hugo.gitlab-ci.yml

lib/gitlab/ci/templates/Security/API-Fuzzing.gitlab-ci.yml

...ab/ci/templates/Security/API-Fuzzing.latest.gitlab-ci.yml

...ab/ci/templates/Security/Container-Scanning.gitlab-ci.yml

lib/gitlab/ci/templates/Security/DAST-API.gitlab-ci.yml

...itlab/ci/templates/Security/DAST-API.latest.gitlab-ci.yml

.../templates/Security/DAST-On-Demand-API-Scan.gitlab-ci.yml

...b/ci/templates/Security/DAST-On-Demand-Scan.gitlab-ci.yml

...i/templates/Security/DAST-Runner-Validation.gitlab-ci.yml

lib/gitlab/ci/templates/Security/DAST.gitlab-ci.yml

lib/gitlab/ci/templates/Security/DAST.latest.gitlab-ci.yml

...itlab/ci/templates/Security/Secure-Binaries.gitlab-ci.yml

lib/gitlab/ci/templates/Terraform/Base.gitlab-ci.yml