Replace jquery.get with Rails.ajax

What does this MR do?

Replace jquery.get with Rails.ajax

In the code below jQuery.get is used in order to download javascript that is then executed. In order to move away from jQuery ajax, we can utilize Rails.ajax which does the same thing.

Screenshots (strongly suggested)

Note: Unfortunately the project import ends in an error, both on master and in my feature branch, the project actually gets created but I assume my GDK is somehow borked. As the error is the same before and after, it is unlikely that this change caused it.

Before	After
template-before	template-after

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

Related to #321859 (closed)