docs: Deprecate old Copilot metrics endpoints closed on April 2, 2026

[Bahtya]

Summary

Relates to: #4136.

The four legacy Copilot metrics endpoints were officially closed down on April 2, 2026 for github.com (as described in the GitHub Docs):

• GetEnterpriseMetrics (GET /enterprises/{enterprise}/copilot/metrics)
• GetEnterpriseTeamMetrics (GET /enterprises/{enterprise}/team/{team_slug}/copilot/metrics)
• GetOrganizationMetrics (GET /orgs/{org}/copilot/metrics)
• GetOrganizationTeamMetrics (GET /orgs/{org}/team/{team_slug}/copilot/metrics)

Per the maintainer's guidance in the issue, these methods are kept in place (as they may still work on GitHub Enterprise Server) but are now marked with // Deprecated: notices directing users to the replacement endpoints:

• GetEnterpriseDailyMetricsReport / GetEnterpriseMetricsReport (for enterprise-level metrics)
• GetOrganizationDailyMetricsReport / GetOrganizationMetricsReport (for org-level metrics)

Note: The 8 new replacement methods were already implemented in #3893. This PR only adds the deprecation notices to the 4 old methods.

Test plan

• Existing tests still pass: go test ./github/... -run TestCopilot
• No code changes — only documentation comments updated
• go vet ./github/... passes with no issues

Bahtya

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[gmlewis]

Thank you, @Bahtya!
LGTM.
Awaiting second LGTM+Approval from any other contributor to this repo before merging.

cc: @stevehipwell - @alexandear - @zyfy29 - @Not-Dhananjay-Mishra - @munlicode

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.74%. Comparing base (5124fac) to head (a265959).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4137   +/-   ##
=======================================
  Coverage   93.74%   93.74%           
=======================================
  Files         211      211           
  Lines       19685    19685           
=======================================
  Hits        18453    18453           
  Misses       1034     1034           
  Partials      198      198           

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[Bahtya]

Wow, thank you so much @gmlewis for the review and approval! 🎉 I really appreciate you taking the time to look at this!

I just signed the Google CLA at https://cla.developers.google.com/ — hopefully the check will update on the next push or re-check. Looking forward to getting a second LGTM! 😄

Thanks for the great project!

[gmlewis]

I just signed the Google CLA at https://cla.developers.google.com/ — hopefully the check will update on the next push or re-check.

Thank you, @Bahtya! Unfortunately, the rescan didn't work.
If the commits were made from a different account than was used to sign the CLA, then either this PR needs to be closed and a new one opened using the email address used to sign the CLA or the CLA needs to be re-signed with the same email address used to create this PR's commits.

Please click on the above link which is https://github.com/google/go-github/pull/4137/checks?check_run_id=70667622891
to get more information about how to fix CLA problems.

[munlicode]

LGTM