Migration Lookup plugin does not return multiple values when matched

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Was previously tagged for IS update and change record which still appear the case.

Did not review or test.

Rerolled #87 on to the MR and rebase against latest 11.x, Updated IS. Hiding all patches.

For what it's worth, I came across this issue and found the patch in #92 📌 Migration Lookup plugin does not return multiple values when matched Needs work worked perfectly for me.

Thanks @shashikant_chauhan!

For added context (see below), I'm processing a JSON file with the url source plugin from the migrate_plus module. As the paragraph mappings come from a `paragraphs` subkey in the JSON structure, I had to do the following in a sub_process plugin. The issue was that only migration lookups only worked for the first migration listed: `blog_paragraphs_copy`. I know this because I tried swapping the order and the `blog_paragraphs_copy_media` then worked but `blog_paragraphs_copy` didn't.

With the patch in #92 📌 Migration Lookup plugin does not return multiple values when matched Needs work both migration lookups are now working successfully. If an item in one migration is found, then it's used, otherwise the other is used.

field_structured_content:
    plugin: sub_process
    source: paragraphs
    process:
      target_id:
        -
          plugin: migration_lookup
          migration:
            - blog_paragraphs_copy
            - blog_paragraphs_copy_media
          source: id
        -
          plugin: extract
          index:
            - 0
      target_revision_id:
        -
          plugin: migration_lookup
          migration:
            - blog_paragraphs_copy
            - blog_paragraphs_copy_media
          source: id
        -
          plugin: extract
          index:
            - 1

Thanks @ckng for the reroll - this was based on the 2890844-65.drupal.patch and now applies cleanly to 10.2.x

Rebased and added the CR.

Patch for Drupal 10.3