[docs] [support workflows] [lnr] Clarifying the usage of cloud activation emails as ownership proofs

Why is this change being made?

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Currently we request a copy of the license file, which was appropriate terminology when the default license provision method were actual license files (rather than cloud activation codes, as is now standard/default).

Given that cloud activation codes are now default, it could be ambiguous to customers regarding if their cloud activation codes (or cloud activation code emails) are valid proof (Example ZD ticket).

This MR updates the list of proofs located on the workflow to explicitly exclude cloud activation codes (& emails) and to direct the actioning engineer to redact activation codes that are provided to support.

Justifications for exclusion

• We don't really have a means to verify cloud activation emails (vs the license validator for legacy licenses) apart from data matching to the record on the Customer Portal.
  • We could data match each item in an activation email (name, start date, end date, etc) to the Zuora tab on the Customer Portal, however that would still be fairly trivial for a malicious actor to fabricate in order to gain administrative access over a billing account.

@gitlab-com/support/licensing-subscription WDYT?

Please also see the proposed ZD macro changes that would reflect this MR

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