Fix parallel jobs dropdown from cutting off in the pipeline graph

What does this MR do?

When on the pipeline graph page where we can see every job, there might be instances where the dropdown that list all of the parallel jobs gets cut off at the bottom. This is because the dropdown html element is inside the pipeline graph container, but the container might be to small to render the full dropdown.

To easily fix this, we add a minimum height to the container bigger than the max-height of the dropdown so we know for sure that the dropdown will never get cut off.

Screenshots

Before

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

Closes #231348 (closed)