…nce (#16399)

Backport of fdd72c5 (PR #16203) from main.

The DotNet-VSTS-Infra-Access variable group only contained the
dn-bot-devdiv-drop-r-code-r PAT, which has been migrated to WIF
(service connection dnceng-devdiv-drop-rw-code-rw-wif). The group is
expired and de-authorized, and because it was referenced at the root
variables level it was resolved at YAML compile time, so the official
pipeline cannot load from rel/18.7 at all.

Nothing has flowed into this branch yet, so no build has failed here.
The change is preventive, so the 18.7 servicing pipeline can load when
it is next needed.

🤖

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 1672b4d9-b4c1-4736-83fa-c8b06a6f966b

* Apply servicing updates to rel/18.7

* Publish RTM release packages as a pipeline artifact

Stage only top-level non-symbol NuGet packages in ReleasePackages and fail when none are found. Publish the artifact only for successful non-PR RTM builds.

Keep the existing isRTM gate, signing, feed publishing, and other artifacts unchanged. Forward manual RTM selection to source-build so package versions agree.

* Restore azure-pipelines.yml for the public PR build

The servicing update removed the public build definition. Restore it
unchanged from rel/18.7. Stop azure-pipelines-official.yml from also
triggering on pull requests, so only the public definition validates them.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Azat Mukhametshin <azatm@microsoft.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>