CI: run nightly/deployment jobs with [ci nightly] tag

Description

CI: run nightly/deployment jobs with [ci nightly] tag

- Using tag sets DEPLOY_DRY_RUN=yes which skips actual deployment of:
  - containers (.docker job)
  - documentation (pages job)
  - Koji packages (repository:koji job)
  - Python wheels (wheel:pypi job)

.gitlab/ci/containers.yml: fix bug with docker:nightly:{el7|bullseye} rules

- From https://docs.gitlab.com/ee/ci/yaml/yaml_optimization.html#merge-details:
  "You can use extends to merge hashes but not arrays", and "rules" is an array
- Instead move the .ci-docker !reference to .docker:nightly

.gitlab/ci/rules.yml: remove .configure-nightly

- ENABLE_NIGHTLY is already set by .ci-nightly-deploy in .gitlab/ci/rules.yml

API Changes and Justification

Backwards Compatible Changes

• This change does not modify any class/function/struct/type definitions in a public C header file or any Python class/function definitions
• This change adds new classes/functions/structs/types to a public C header file or Python module

Backwards Incompatible Changes

• This change modifies an existing class/function/struct/type definition in a public C header file or Python module
• This change removes an existing class/function/struct/type from a public C header file or Python module

If any of the Backwards Incompatible check boxes are ticked please provide a justification why this change is necessary and why it needs to be done in a backwards incompatible way.

Review Status

Please provide details on any reviews related to this change and and the associated reviewers.