Support variable expansion on environment:auto_stop_in

What does this MR do and why?

Support variable expansion for environment:auto_stop_in.

Implementation follows the proposal laid out in #365140 (closed)

• We loose the auto_stop_in validation to String type from duration parser's validation.
• Renew the environments.auto_stop_in with variable expansion when a deployment succeeded.
• Track the parser error in Sentry/Log. This is helpful to debug user errors.

Documentation changes will be covered in a separate MR.

Screenshots or screen recordings

auto_stop_in_variable_expansion

How to set up and validate locally

• On a test project in local, use the below simple ci configuration file and trigger pipeline.

.gitlab-ci.yml

image: alpine:latest

stages:
  - deploy_preprod
  - deploy_prod

.deploy: &deploy
  script:
    - echo "env is $JOB_ENVIRONMENT"
    - echo "TTL is $TTL"
  environment:
    name: $JOB_ENVIRONMENT
    auto_stop_in: $TTL

deploy_prod:
  stage: deploy_prod
  <<: *deploy
  variables:
    JOB_ENVIRONMENT: 'prod'
    TTL: '14 days'

deploy_preprod:
  stage: deploy_preprod
  <<: *deploy
  variables:
    JOB_ENVIRONMENT: 'preprod'
    TTL: '2 days'

• We should observe the TTL variable being substituted with value to the environment auto_stop_at field as shown in the UI in video above.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #365140 (closed)