circuitv2: flaky TestReservationFailures

[marten-seemann]

https://github.com/libp2p/go-libp2p/actions/runs/3208002096/jobs/5243462098

  === RUN   TestReservationFailures/invalid_time
      reservation_test.go:100: 
          	Error Trace:	/home/runner/work/go-libp2p/go-libp2p/p2p/protocol/circuitv2/client/reservation_test.go:100
          	Error:      	"error writing reservation message: Application error 0x0: peer:12D3KooWQMrNzVJdPSsgvtwFvZ4jPLYNjXZ1Xc4BAPWtA4MGAtMy: cannot reserve inbound connection: resource limit exceeded" does not contain "received reservation with expiration date in the past"
          	Test:       	TestReservationFailures/invalid_time
  === RUN   TestReservationFailures/invalid_voucher
  --- FAIL: TestReservationFailures (0.89s)
      --- PASS: TestReservationFailures/unsupported_protocol (0.20s)
      --- PASS: TestReservationFailures/wrong_message_type (0.14s)
      --- PASS: TestReservationFailures/unknown_status (0.17s)
      --- FAIL: TestReservationFailures/invalid_time (0.18s)
      --- PASS: TestReservationFailures/invalid_voucher (0.20s)