feat: wait for meilisearch index creation to succeed

[regisb]

In search.meilisearch.create_indexes, we were not waiting for the index creation tasks to complete. This was causing a potential race condition, where the create_indexes function would fail because it took a few seconds for the index creation to succeed.

See the relevant conversation here:
openedx/edx-platform#35743 (comment)

[openedx-webhooks]

Thanks for the pull request, @regisb!

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[regisb]

@ormsbee can you please review this, since you also reviewed #164?

[ormsbee]

Made a new 4.1.1 release for this. Should push to PyPI shortly.