Add reasonable timeouts to all workflows (#7499)

Turns out the default timeout for github actions is 6 hours (!). This PR
sets some reasonable default for all workflows, the ones invoking cargo
in some way are limited to 60 minutes and the remaining ones to
10-15mins.

.github/workflows/labels.yml

@@ -16,6 +16,7 @@ on:
 jobs:
   label:
     runs-on: ubuntu-latest
+    timeout-minutes: 10
     steps:
       - name: Check for a "do-not-merge" label
         uses: mheap/github-action-required-labels@v3