csi: don't wait to fire initial unmount RPC (#12102)

In PR #11892 we updated the `csi_hook` to unmount the volume locally
via the CSI node RPCs before releasing the claim from the server. The
timer for this hook was initialized with the retry time, forcing us to
wait 1s before making the first unmount RPC calls.

Use the new helper for timers to ensure we clean up the timer nicely.

client/allocrunner/csi_hook.go

@@ -9,6 +9,7 @@ import (
 	hclog "github.com/hashicorp/go-hclog"
 	multierror "github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/nomad/client/pluginmanager/csimanager"
+	"github.com/hashicorp/nomad/helper"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/nomad/plugins/drivers"
 )
@@ -286,13 +287,13 @@ func (c *csiHook) unmountWithRetry(pair *volumeAndRequest) error {
 	defer cancel()
 	var err error
 	backoff := time.Second
-	ticker := time.NewTicker(backoff)
-	defer ticker.Stop()
+	t, stop := helper.NewSafeTimer(0)
+	defer stop()
 	for {
 		select {
 		case <-ctx.Done():
 			return err
-		case <-ticker.C:
+		case <-t.C:
 		}
 
 		err = c.unmountImpl(pair)
@@ -306,7 +307,7 @@ func (c *csiHook) unmountWithRetry(pair *volumeAndRequest) error {
 				backoff = c.maxBackoffInterval
 			}
 		}
-		ticker.Reset(backoff)
+		t.Reset(backoff)
 	}
 	return nil
 }