Add new ci_max_total_yaml_size_bytes application setting

What does this MR do and why?

Addressing issue. Adding a new application setting called: ci_max_total_yaml_size_bytes

Screenshots or screen recordings

UPDATE The UI for changing of the limit was removed at this stage.

Migrations

How to set up and validate locally

1. Set low limit via command line: ApplicationSetting.update(ci_max_total_yaml_size_bytes: 100)
2. Create a pipeline yml file, including other files.
3. Run pipeline and verify errors.

When CI/CD configuration size in bytes is higher then limit: -> we get the error message

When CI/CD configuration size in bytes is higher then limit, but the feature flag is disabled: -> we see a valid pipeline

See screenshot

When CI/CD configuration size in bytes is lower then limit: -> we see a valid pipeline

See screenshot

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.