fix(ci): stable deb promotion with the shared release component and non plugins tags

[tuntoja]

Fixes CTOR-2557

Description

Two bugs hit while promoting release-20260900 to stable (follow-up of #6462 / #6463):

• get-environment: on stable, the latest-tag lookup read match[1] of every tag; a non plugins-* tag in the 10 latest (windows-20260900) crashed every stable run (TypeError: Cannot read properties of null). Non matching tags are now skipped
• promote-deb: the batch promote deduced the stable release component by diffing the reference package's suite associations before/after the legacy upload
• Since the domain merge, testing and stable share their content: bookworm/main is one release component already associated at delivery, so the diff was empty and the admin-only fallback listing answered 403 (every multi-package deb promote failed; single-package modules were unaffected)
• When the diff is empty and the reference package has a single association, that association is reused
• pulp token refresh: loops refreshed the OIDC token only every 40 iterations; with ~2.5 s lookups the check could land past the ~5 min expiry, and every call until the next 40th got a 403 (61 false ❌ presence on jammy/noble during the release-20260900 check). refresh_pulp_token is now called on every iteration (no-op while the token is < 240 s old), in check-deb, deliver-deb, deliver-rpm and promote-deb
• Validated in CI conditions (temporary release-20260900-tun-next branch): 683 plugins packages promoted and published on bookworm/trixie/jammy/noble, checked against pulp afterwards
• Same fix on master in the companion PR