Pull Request resolves #47335 .

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

When 'Use Global' is selected for Image Class in the Articles
module, the global value was not being applied to the figure tag.
The code was checking if float_intro was empty, but 'Use Global'
is not empty — it's a literal string. Fixed by also checking if
the value equals 'Use Global' and fetching the actual global
value in that case.

Testing Instructions

1. Set a default Image Class in Articles e.g. "image-intro"
2. Use the Articles site module
3. Set Image Class to "Use Global"
4. Check the HTML output
5. Figure tag should now include the global image class

Actual result BEFORE applying this Pull Request

Expected result AFTER applying this Pull Request

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• [✅] No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• [✅] No documentation changes for manual.joomla.org needed