refactor: back the e2e Eventually helpers with testify

Delegate the hand-rolled deadline loops to require.Eventually and
require.EventuallyWithT instead of open-coding the polling.

tests/e2e/harness/wait.go

@@ -6,44 +6,25 @@ import (
 	"context"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // Eventually polls cond until it returns true or the timeout expires.
 // Replaces every `sleep N; <probe>` loop in the bash scripts.
 func Eventually(t *testing.T, cond func() bool, timeout, interval time.Duration, msgAndArgs ...any) {
 	t.Helper()
-	deadline := time.Now().Add(timeout)
-	for {
-		if cond() {
-			return
-		}
-		if time.Now().After(deadline) {
-			if len(msgAndArgs) == 0 {
-				t.Fatalf("Eventually: condition not met within %s", timeout)
-			}
-			t.Fatalf("Eventually: condition not met within %s: %v", timeout, msgAndArgs)
-		}
-		time.Sleep(interval)
-	}
+	require.Eventually(t, cond, timeout, interval, msgAndArgs...)
 }
 
 // EventuallyErr is like Eventually but lets cond return an error for the
 // failure message. Useful when the probe itself yields diagnostic detail.
 func EventuallyErr(t *testing.T, cond func() error, timeout, interval time.Duration) {
 	t.Helper()
-	deadline := time.Now().Add(timeout)
-	var lastErr error
-	for {
-		if err := cond(); err == nil {
-			return
-		} else {
-			lastErr = err
-		}
-		if time.Now().After(deadline) {
-			t.Fatalf("EventuallyErr: condition not met within %s: %v", timeout, lastErr)
-		}
-		time.Sleep(interval)
-	}
+	require.EventuallyWithT(t, func(c *assert.CollectT) {
+		assert.NoError(c, cond())
+	}, timeout, interval)
 }
 
 // RetryWithReset runs fn as "attempt-1"; on failure it calls ResetAllNodes and