Resolve "The "Project slug" field does not get filled with the "Project name" field when creating a project using a template with the new experimental UI"

What does this MR do?

Our JQuery-based code for project creation relies on .active class for active tab to work

Introduction of new UI removed bootstrap tabs and broke this code. Since this is a part of an experiment we need to maintain functionality for both options, so we're adding logic to legacy_container to add active class

Related issue: #222810 (closed)

Screenshots

N/A

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