ci: add explicit timeout-minutes to prevent resource exhaustion

Without a job-level wall-clock cap a hung setup or install step can
consume runner minutes indefinitely. kind-e2e.yaml already limits the
test run itself to 90 m via -timeout=90m but has no job ceiling;
setting timeout-minutes: 120 gives 30 m of headroom for cluster setup
and teardown. knative-downstream.yaml had no timeout at all;
timeout-minutes: 60 is a conservative cap for downstream unit tests.

Made-with: Cursor

Author: Ankitsinghsisodya

.github/workflows/kind-e2e.yaml

@@ -13,6 +13,7 @@ jobs:
   e2e-tests:
     name: e2e tests
     runs-on: ubuntu-latest
+    timeout-minutes: 120
     strategy:
       fail-fast: false # Keep running if one leg fails.
       matrix:

.github/workflows/knative-downstream.yaml

@@ -40,6 +40,7 @@ jobs:
             org: knative-extensions
 
     runs-on: ubuntu-latest
+    timeout-minutes: 60
     env:
       GOPATH: ${{ github.workspace }}
     steps: