roachtest: wait longer for token return

Previously tokens needed to be returned within 5 seconds of stopping the
workload. This resulted in failures in some of the perturbation/* tests
when using apply-to-all for replAC. This change bumps the window to 5
minutes to allow more times for the tokens to be returned.

Epic: none

Release note: None

pkg/cmd/roachtest/roachtestutil/validation_check.go

@@ -163,6 +163,6 @@ func ValidateTokensReturned(
 				}
 			}
 			return nil
-		}, 5*time.Second)
+		}, 5*time.Minute)
 	}
 }