Move Jobs/Deploy/ECS.gitlab-ci.yml to the top level of AutoDevOps template

What does this MR do?

When we override a specific template of the Auto DevOps, we can use include:remote keyword like below:

include:
  - template: Auto-DevOps.gitlab-ci.yml
  - remote: https://gitlab.com/gitlab-org/gitlab/-/raw/canary-ingress-rails/lib/gitlab/ci/templates/Jobs/Deploy.latest.gitlab-ci.yml

However, currently users need to comment-out the Jobs/Deploy/ECS.gitlab-ci.yml inclusion from the overriding template, because it raises an error that it includes the template twice.

include:
  - template: Jobs/Deploy/ECS.gitlab-ci.yml

As an example, please see https://gitlab.com/dosuken123/new-sentimentality/-/blob/master/.gitlab-ci.yml#L15-17 and !39438 (diffs)

We should not include inside include as this is a error prone approach, instead we should include the template at the top-level.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team