Run the networking e2e tests for sdsmint variant (#1155)

Run the networking suite a second time against the sdsmint (MITM)
egress gateway, so the egress path is covered on both gateway variants
    rather than only on passthrough.

A part of #823 

From
https://github.com/agent-substrate/substrate/actions/runs/32786529664/job/97619491954?pr=1155,
this change adds about 70 seconds to the `e2e-test` workflow:

   - Step `Deploy MITM egress demo`: 8s
   - Step `Run E2E tests (networking, MITM egress)`: 33s
   - Step `Run E2E tests (networking, MITM egress, micro-VM)`: 30s

> It's a good idea to open an issue first for discussion.

- [x] Tests pass
- [x] Appropriate changes to documentation are included in the PR

.github/workflows/pr-workflow.yaml

@@ -133,6 +133,21 @@ jobs:
         E2E_EGRESS_MITM: "1"
         E2E_SANDBOX_CLASS: microvm
       run: hack/run-e2e-kind.sh ./internal/e2e/suites/egressmitm -v -args --no-color
+    - name: Deploy MITM egress demo
+      # The networking suite's egress tests need a fixture that trusts the
+      # CA used by sdsmint.
+      run: |
+        hack/install-ate-kind.sh --deploy-demo-egress-mitm
+        hack/install-ate-kind.sh --deploy-demo-egress-microvm-mitm
+    - name: Run E2E tests (networking, MITM egress)
+      env:
+        E2E_EGRESS_MITM: "1"
+      run: hack/run-e2e-kind.sh ./internal/e2e/suites/networking -v -args --no-color
+    - name: Run E2E tests (networking, MITM egress, micro-VM)
+      env:
+        E2E_EGRESS_MITM: "1"
+        E2E_SANDBOX_CLASS: microvm
+      run: hack/run-e2e-kind.sh ./internal/e2e/suites/networking -v -args --no-color
     - name: Dump diagnostics on failure
       if: failure()
       run: |