throw a TypeError when trying to merge a list with a mapping when `me…

[tomdoherty]

throw a TypeError when trying to merge a list with a mapping when merge_lists=True

What does this PR do?

What issues does this PR fix or reference?

Fixes #67092

Previous Behavior

Silently drops values

New Behavior

Throws TypeError

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

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• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

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[lkubb]

I don't think this is the correct (default) behavior since this function intends to emulate dict.update. This also happens for nested dicts, where a non-dict value overwrites the whole nested dict. If you want to enforce the same structure for both dicts, I would consider adding a strict switch or a separate function that enforces this.

Note that this should target 3008 since it's either breaking compatibility (a lot) or, if going with strict, introducing new functionality.