Change `Convert CI file` functionality to use Duo Developer
## Problem
The Convert to GitLab CI Flow has not been improved in a long time. It only targets Jenkins pipeline files and has not been meaningfully improved in a long time.
## Desired Outcome
The functionality behind Convert to GitLab CI Flow is extended beyond Jenkins files and is more likely to work correctly.
## Proposal
1. Replace the dedicated flow with the Duo Developer setup and specific instructions. https://gitlab.com/gitlab-org/gitlab/-/merge_requests/230512/ shows an example implementation for using Duo Developer with a specific goal behind a button.
2. Through https://gitlab.com/gitlab-org/gitlab/-/work_items/593202+ the flow will have access to verify GitLab CI/CD pipeline, instruct the agent in the goal to make use of this.
3. Extend the flow to other common CI pipelines:
1. Target migration setups mentioned [in docs](https://gitlab.com/gitlab-org/gitlab/-/work_items/597606#note_3328259163)
2. Relevant file types to show the button (to be confirmed):
* `Jenkinsfile`
* `.github/workflows/*.y(a)ml`
* `.circleci/config.yml`
* `bamboo-specs/*.(yml|java)`
* `.teamcity/*.kts`
* `azure-pipelines.yml`
* `.travis.yml`
issue