Add GraphQL update and delete mutations for the Anthropic Compliance integration

What does this MR do and why?

Adds GraphQL mutations to update and delete the Anthropic Compliance integration of a top-level group, behind the claude_code_compliance_api_ingestion feature flag:

• anthropicComplianceIntegrationUpdate takes either a new apiKey (verified with Anthropic before it is saved) or enabled to turn syncing on or off. Re-enabling without a new key checks the stored key again.
• anthropicComplianceIntegrationDelete removes the integration and its transcript walk state. Ingested sessions are kept.
• Owner only. Checking a key with Anthropic uses the same rate limits as create. Adds the NOT_FOUND error reason and audit events for both actions.

Two small related changes:

• The Group.anthropicComplianceIntegration field description now says it also returns null when the user cannot read the integration, matching orbitAccess.
• GraphQL variable logging now filters apiKey. The case-sensitive /key$/ filter does not match the camelCase variable used by the create and update mutations.

References

• Builds on !264339 (merged) (merged)
• https://gitlab.com/gitlab-org/gitlab/-/work_items/628487

Screenshots or screen recordings

Not a UI change.

How to set up and validate locally

bundle exec rspec \
  ee/spec/requests/api/graphql/mutations/ai/compliance/anthropic/integrations/update_spec.rb \
  ee/spec/requests/api/graphql/mutations/ai/compliance/anthropic/integrations/delete_spec.rb \
  spec/lib/gitlab/graphql/query_analyzers/ast/logger_analyzer_spec.rb

MR acceptance checklist

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