ci(r2-12): delete no-op nightly E2E workflow + redundant integration matrix (07/S-3, 07/P-5)

- v2-e2e.yml deleted: its `--filter Category=E2E` matches zero tests repo-wide (the
  E2ETests project doesn't exist) so it reported a permanent false green; and its
  docker-dev fleet binds the LAN-only shared GLAuth (10.100.0.35:3893) + builds local
  images, so it isn't hosted-runner-bootable anyway. FOLLOW-UP: when a runner-reachable
  fleet + a real tests/Server/...E2ETests land, add a fresh workflow WITH a zero-match
  guard (fail if Category=E2E matches nothing).
- v2-ci.yml integration matrix removed: fully redundant with the unit-tests leg, which
  already runs both Host.IntegrationTests + OpcUaServer.IntegrationTests under the
  identical filter, fixtureless, gated at MIN_EXECUTED=1. No coverage lost. The S-2
  option-#2 fixture-backed-leg follow-up is preserved as a NOTE comment in the workflow.
Header comments updated; YAML validates; jobs are now build -> unit-tests.

.github/workflows/v2-e2e.yml

@@ -1,57 +0,0 @@
-# Nightly E2E job. Runs against the docker-dev four-node fleet (admin-a +
-# admin-b + driver-a + driver-b + SQL + LDAP + Traefik). Trigger:
-#   - cron at 03:00 UTC daily
-#   - workflow_dispatch from the Actions UI for on-demand runs
-#
-# The E2E test project (tests/Server/ZB.MOM.WW.OtOpcUa.E2ETests) does not yet
-# exist — it lands when the F-series follow-ups F10/F11/F12 wire enough of the
-# SDK/historian/probe so an end-to-end driver round-trip is meaningful. Until
-# then this workflow is a green no-op (the `--filter Category=E2E` matches
-# zero tests, and `dotnet test` returns 0).
-
-name: v2-e2e
-
-on:
-  schedule:
-    - cron: "0 3 * * *"
-  workflow_dispatch: {}
-
-env:
-  DOTNET_NOLOGO: "1"
-  DOTNET_CLI_TELEMETRY_OPTOUT: "1"
-
-jobs:
-
-  e2e:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-dotnet@v4
-        with:
-          dotnet-version: 10.0.x
-
-      - name: dotnet restore
-        run: dotnet restore ZB.MOM.WW.OtOpcUa.slnx
-
-      - name: Build docker-dev fleet
-        run: docker compose -f docker-dev/docker-compose.yml up -d --build
-
-      - name: Wait for cluster
-        run: |
-          for i in $(seq 1 30); do
-            if curl -sf http://localhost/health/active >/dev/null; then
-              echo "Admin leader healthy after ${i}s"
-              exit 0
-            fi
-            sleep 2
-          done
-          echo "Timed out waiting for /health/active"
-          docker compose -f docker-dev/docker-compose.yml logs --tail=200
-          exit 1
-
-      - name: dotnet test (E2E only)
-        run: dotnet test --configuration Release --filter "Category=E2E"
-
-      - name: Tear down
-        if: always()
-        run: docker compose -f docker-dev/docker-compose.yml down -v