Prepopulates the pipeline editor with a 3 stage template

What does this MR do?

This MR prepoulates blank CI files in the Pipeline Editor with an explanatory template, as laid out in #300501 (closed) and updates the drawer text to align, as laid out in #331788 (closed). (Note: This only applies when the the file is a new CI file.)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• I have included a changelog entry, or it's not needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have self-reviewed this MR per code review guidelines.
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)

Related to #300501 (closed), #331788 (closed)