Fix workflow:rules not accessing passed-upstream and trigger variables

What does this MR do?

• Related to #206929 (closed)
• Previous attempt: !44935 (merged)
• Revert: !45433 (merged)

This is the second attempt to fix this problem.

Example CI config:

workflow:
  rules:
    - if: $SOME_VARIABLE

test:
  script: echo test

Normally, we should run this pipeline with passing SOME_VARIABLE in it. However, when running this pipeline with trigger keyword or trigger API, workflow::rules can not read the passed variable.

In Ci::CreatePipelineService, we run https://gitlab.com/gitlab-org/gitlab/-/blob/5aae54af261e21b5a17c04967d8d8f0d84730c60/lib/gitlab/ci/pipeline/chain/seed.rb#L25 in Gitlab::Ci::Pipeline::Chain::Seed section. seeds_block is passed through Ci::CreatePipelineService in the places where some attributes are passed to the to-be-created pipeline. For example; in Ci::PipelineTriggerService and Ci::CreateDownstreamPipelineService, we are using it to pass variables.

The problem is, Gitlab::Ci::Pipeline::Chain::EvaluateWorkflowRules is run before Gitlab::Ci::Pipeline::Chain::Seed, so the workflow:rules can't read the variables.

This MR fixes this.

This fix is behind a feature flag ci_seed_block_run_before_workflow_rules. #270439 (closed)

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Related to #206929 (closed)