[MAINT] Consolidate ID in EMU group mapping resource

[deiga]

@deiga I've only just spotted this, but why hasn't the ID be corrected to match the input ID? The resource is scoped to the EMU group, so I'd expect the ID to be <group-id>:<team-id> as it is in the import? Also why is the ID using 3 parts instead of the 2 parts used for this pattern elsewhere in the re-written provider code?

Originally posted by @stevehipwell in #3163 (comment)

[github-actions]

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