Fix TestAccessControlWithSSLCertDir/[subgroup]_invalid_token_test_should_redirect_back flaky test

Job #736200716 failed for bd774244:

    helpers_test.go:31: time="2020-09-14T10:28:08Z" level=fatal msg="could not create pages daemon" error="signal: interrupt"
--- FAIL: TestAccessControlWithSSLCertDir (1.68s)
    --- PASS: TestAccessControlWithSSLCertDir/project_with_access (0.17s)
    --- PASS: TestAccessControlWithSSLCertDir/project_without_access (0.17s)
    --- PASS: TestAccessControlWithSSLCertDir/invalid_token_test_should_redirect_back (0.17s)
    --- PASS: TestAccessControlWithSSLCertDir/no_project_should_redirect_to_login_and_then_return_404 (0.17s)
    --- PASS: TestAccessControlWithSSLCertDir/no_project_should_redirect_to_login_and_then_return_404#01 (0.16s)
    --- PASS: TestAccessControlWithSSLCertDir/[subgroup]_project_with_access (0.17s)
    --- PASS: TestAccessControlWithSSLCertDir/[subgroup]_project_without_access (0.18s)
    --- FAIL: TestAccessControlWithSSLCertDir/[subgroup]_invalid_token_test_should_redirect_back (0.17s)
    --- PASS: TestAccessControlWithSSLCertDir/[subgroup]_no_project_should_redirect_to_login_and_then_return_404 (0.16s)
    --- PASS: TestAccessControlWithSSLCertDir/[subgroup]_no_project_should_redirect_to_login_and_then_return_404#01 (0.17s)