platformtest: fix bandwidth-limiting-related panics (missing BucketCapacity in sender/receiver config)

panic while running test: invalid config`Ratelimit` field invalid: BucketCapacity must not be zero
main.runTestCase.func1.1
	/home/cs/zrepl/zrepl/platformtest/harness/harness.go:190
runtime.gopanic
	/home/cs/go1.13/src/runtime/panic.go:679
github.com/zrepl/zrepl/endpoint.NewSender
	/home/cs/zrepl/zrepl/endpoint/endpoint.go:68
github.com/zrepl/zrepl/platformtest/tests.replicationInvocation.Do
	/home/cs/zrepl/zrepl/platformtest/tests/replication.go:87
github.com/zrepl/zrepl/platformtest/tests.ReplicationFailingInitialParentProhibitsChildReplication
	/home/cs/zrepl/zrepl/platformtest/tests/replication.go:925
main.runTestCase.func1
	/home/cs/zrepl/zrepl/platformtest/harness/harness.go:193
main.runTestCase
	/home/cs/zrepl/zrepl/platformtest/harness/harness.go:194
main.HarnessRun
	/home/cs/zrepl/zrepl/platformtest/harness/harness.go:107
main.main
	/home/cs/zrepl/zrepl/platformtest/harness/harness.go:42
runtime.main
	/home/cs/go1.13/src/runtime/proc.go:203
runtime.goexit
	/home/cs/go1.13/src/runtime/asm_amd64.s:1357

fixup for f5f269bfd5 (bandwidth limiting)

platformtest/tests/replication.go

@@ -20,6 +20,7 @@ import (
 	"github.com/zrepl/zrepl/replication/logic"
 	"github.com/zrepl/zrepl/replication/logic/pdu"
 	"github.com/zrepl/zrepl/replication/report"
+	"github.com/zrepl/zrepl/util/bandwidthlimit"
 	"github.com/zrepl/zrepl/util/limitio"
 	"github.com/zrepl/zrepl/util/nodefault"
 	"github.com/zrepl/zrepl/zfs"
@@ -63,9 +64,10 @@ func (i replicationInvocation) Do(ctx *platformtest.Context) *report.Report {
 	}
 
 	senderConfig := endpoint.SenderConfig{
-		FSF:     i.sfilter.AsFilter(),
-		Encrypt: &nodefault.Bool{B: false},
-		JobID:   i.sjid,
+		FSF:            i.sfilter.AsFilter(),
+		Encrypt:        &nodefault.Bool{B: false},
+		JobID:          i.sjid,
+		BandwidthLimit: bandwidthlimit.NoLimitConfig(),
 	}
 	if i.senderConfigHook != nil {
 		i.senderConfigHook(&senderConfig)
@@ -75,6 +77,7 @@ func (i replicationInvocation) Do(ctx *platformtest.Context) *report.Report {
 		JobID:                      i.rjid,
 		AppendClientIdentity:       false,
 		RootWithoutClientComponent: mustDatasetPath(i.rfsRoot),
+		BandwidthLimit:             bandwidthlimit.NoLimitConfig(),
 	}
 	if i.receiverConfigHook != nil {
 		i.receiverConfigHook(&receiverConfig)