fix: replace 'circle' with 'team' in CircleHelper (fixes #2249)

[abbasnadir]

Didn't find any instance of circle or circles other than in lib/CircleHelper. Fixed as per the guidance of enjeck.

[enjeck]

Thanks. Can you please sign your commit: https://github.com/nextcloud/tables/pull/2455/checks?check_run_id=70921473850

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