cleanup-self-hosted-runner: clean up idle runners earlier

The original idea was to wait at least 3 hours before deleting a VM, to
avoid interfering with long-running workflows.

Now that we have a way to query whether the runner _is_ busy, we do not
need to wait that long. Basically, we only need to ensure that the
runner had a chance to register itself and to then pick up the job.
Typically, this takes around 6-7 minutes, so waiting for an hour is
probably even a tad conservative.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

.github/workflows/cleanup-self-hosted-runners.yml

@@ -34,7 +34,7 @@ jobs:
         inlineScript: |
           active_vms=$(az vm list -g ${{ secrets.AZURE_RESOURCE_GROUP }} | jq -c '.[] | {name,timeCreated}')
           current_time=$(date +%s)
-          three_hours_ago=$(($current_time - 3 * 3600))
+          one_hour_ago=$(($current_time - 3600))
 
           if [ -z "$active_vms" ]; then
               echo "No active VMs found, nothing to do."
@@ -51,8 +51,8 @@ jobs:
                   jq -r '.timeCreated | sub("\\.[0-9]+[+-][0-9]+:[0-9]+$"; "") | sub("T"; " ")')"
               vm_creation_time=$(TZ=UTC date -d "$vm_creation_time_string" +%s)
               
-              if [ "$three_hours_ago" -lt "$vm_creation_time" ]; then
-                  echo "The VM ${vm_name} was created less then 3 hours ago and shouldn't be deleted yet. Skipping."
+              if [ "$one_hour_ago" -lt "$vm_creation_time" ]; then
+                  echo "The VM ${vm_name} was created less then 1 hour ago and shouldn't be deleted yet. Skipping."
               elif test true = "$(if test ! -f .cli-authenticated; then
                       ./gh-cli-auth-as-app.sh &&
                       >.cli-authenticated # only authenticate once