Geo Nodes - Title Spacing

What does this MR do?

Closes #225628 (closed)

The Geo Node Title was using the flex box and spacing from the button to have the expected top and bottom spacing. However, when the button isn't there, it loses its bottom spacing due to a :last-child selector on .page-title that sets margin-bottom: 0;

This change adds .gl-mb-5\! to add the margin-bottom: 1rem (16px) that is expected to exist in all scenarios. I had to switch the syntax in the HAML file to support the \! part of the class.

Screenshots

	w/ Button	w/o Button
before
after

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
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• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
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Closes #225628 (closed)