The number of SQL queries in Ci::CreatePipelineService

This issue is created based on these 3 issues:

• API endpoint POST /projects/:project_id/trigger/pipeline executes more than 100 SQL queries
• API endpoint POST /projects/:id/pipeline executes more than 100 SQL queries
• Controller Projects::PipelinesController#create executes more than 100 SQL queries

In those issues, we try to investigate why those endpoints have more than 100 SQL queries. We realized that all three issues use the same service Ci::CreatePipelineService. And we decided to handle them all in this single issue. (Slack discussion)

Note ❗ => We are currently working on moving pipeline processing to async, and we think that can also help this issue.

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Some reference => #321695 (closed)

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Track: https://log.gprd.gitlab.net/goto/31d8fcc73a71895dca3d25d0efe91f91