NEXT-00000 - Changed media partial loaded event name

[En0Ma1259]

1. Why is this change necessary?

MediaUrlLoader partial event is wrong

2. What does this change do, exactly?

Changed event name partial.media.loaded -> media.partial_loaded.
Event name will be generated like this $this->definition->getEntityName() . '.partial_loaded' in PartialEntityLoadedEvent

3. Describe each step to reproduce the issue or behaviour.

Load Partial Media

4. Please link to the relevant issues (if any).

5. Checklist

• I have rebased my changes to remove merge conflicts
• I have written tests and verified that they fail without my change
• I have created a changelog file with all necessary information about my changes
• I have written or adjusted the documentation according to my changes
• This change has comments for package types, values, functions, and non-obvious lines of code
• I have read the contribution requirements and fulfil them.

[shopware-github-importer]

Hello,

thank you for creating this pull request.
I have opened an issue on our Issue Tracker for you. See the issue link: https://issues.shopware.com/issues/NEXT-35785

Please use this issue to track the state of your pull request.