[Issue] Use one format in all places for array_merge

[m2-assistant]

This issue is automatically created based on existing pull request: #30002: Use one format in all places for array_merge

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Fix potential issues when no items in array
Convert all array_merge into single format

Description (*)

Related Pull Requests

Fixed Issues (if relevant)

1. Fixes magento/magento2#<issue_number>

Manual testing scenarios (*)

1. ...
2. ...

Questions or comments

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)

[magento-engcom-team]

Hi @m2-assistant[bot]. Thank you for your report.
The issue has been fixed in #30002 by @ihor-sviziev in 2.4-develop branch
Related commit(s):

• a2b93809864fa6dd645d44a5c818266459f53b95
• f6c4cbd23fca8a7cd7b73c4c609f5179d644d527
• 7f9c3347be167837eb2ad5a6eca76c183a7a274a

The fix will be available with the upcoming 2.4.2 release.