`TestPostageDirectAndDeferred` data race

[acud]

=== RUN   TestPostageDirectAndDeferred
=== RUN   TestPostageDirectAndDeferred/bytes:_deferred
=== RUN   TestPostageDirectAndDeferred/bytes:_direct_upload
=== RUN   TestPostageDirectAndDeferred/bzz:_deferred
=== RUN   TestPostageDirectAndDeferred/bzz:_direct_upload
    api_test.go:390: got response status 402 Payment Required, want 201 Created
==================
WARNING: DATA RACE
Read at 0x00c0005fb0b0 by goroutine 66:
  runtime.mapaccess2_faststr()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/runtime/map_faststr.go:107 +0x0
  github.com/ethersphere/bee/pkg/api_test.(*chanStorer).Has()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:456 +0x684
  github.com/ethersphere/bee/pkg/api_test.TestPostageDirectAndDeferred.func2()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:404 +0x611
  testing.tRunner()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1306 +0x47

Previous write at 0x00c0005fb0b0 by goroutine 35:
  runtime.mapassign_faststr()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/runtime/map_faststr.go:202 +0x0
  github.com/ethersphere/bee/pkg/api_test.(*chanStorer).drain()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:432 +0xb1
  github.com/ethersphere/bee/pkg/api_test.newChanStore·dwrap·1()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:424 +0x47

Goroutine 66 (running) created at:
  testing.(*T).Run()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1306 +0x726
  github.com/ethersphere/bee/pkg/api_test.TestPostageDirectAndDeferred()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:386 +0x9b6
  testing.tRunner()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1306 +0x47

Goroutine 35 (running) created at:
  github.com/ethersphere/bee/pkg/api_test.newChanStore()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:424 +0x164
  github.com/ethersphere/bee/pkg/api_test.newTestServer()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:[114](https://github.com/ethersphere/bee/runs/6276791763?check_suite_focus=true#step:11:114) +0x4a4
  github.com/ethersphere/bee/pkg/api_test.TestPostageDirectAndDeferred()
      /Users/runner/work/bee/bee/pkg/api/api_test.go:349 +0x504
  testing.tRunner()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /Users/runner/hostedtoolcache/go/1.17.9/x64/src/testing/testing.go:1306 +0x47
==================
    api_test.go:405: chunk not received through the direct channel
    testing.go:[115](https://github.com/ethersphere/bee/runs/6276791763?check_suite_focus=true#step:11:115)2: race detected during execution of test
=== CONT  TestPostageDirectAndDeferred
    testing.go:1152: race detected during execution of test
--- FAIL: TestPostageDirectAndDeferred (0.28s)
    --- PASS: TestPostageDirectAndDeferred/bytes:_deferred (0.05s)
    --- PASS: TestPostageDirectAndDeferred/bytes:_direct_upload (0.04s)
    --- PASS: TestPostageDirectAndDeferred/bzz:_deferred (0.10s)
    --- FAIL: TestPostageDirectAndDeferred/bzz:_direct_upload (0.07s)