[BUG] Metadata index_name still gets changed when moving metadata in list

[csidirop]

Description

After #1147 has been resolved, it looked like everything worked. To recap: changing a metadata entry and saving it worked! But moving a metadata entry up or down in the list triggers again a renaming of the index_name:

4: The value of the field "index_name" has been changed from "type" to "type0" as it is required to be unique.

To be honest, I think we could ignore this because everything works as aspected as far as I saw it. But users could be irritated by that.

[csidirop]

In addition: We could "fix" this by modifying the index_name of the translation. e.g: $translatedRecord->setIndexName($indexName."_".$siteLanguage->getLanguageId()); (here)

But I do not know if this is a good solution or just a workaround. If you think this thats ok, I can prepare a PR.

[csidirop]

Btw. Solving this fixes also following issues:

• Incorrectly assigned Data Format entries (e.g.: two MODS entries with false paths or entries not in MetadataDefaults.php) (first mentioned in [BUG] Metadata and structure translation entries #1147)
• Calendar overview stopped working / showed nothing (getIssuesFromDocuments() called $document->getYear() but year was false indexed (volume instead of year) and thues there could no calendar get build)
• Metadata is not translated when you change the language (in PageView)

All those issues are fixed by my proposal. So I'll open a PR and be open for feedback or changes.

Edit: Some of those errors coming from a faulty DFG-Viewer setup slub/dfg-viewer#283