tell-based-protocol: ConcurrentModificationException during replay

When transitioning from a connecting connection to a local connection, if we have outstanding read replies and immediate aborts, the replay will fail with a ConcurrentModificationException:

java.util.ConcurrentModificationException
at java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:719)[:1.8.0_121]
at java.util.LinkedHashMap$LinkedValueIterator.next(LinkedHashMap.java:747)[:1.8.0_121]
at org.opendaylight.controller.cluster.databroker.actors.dds.ProxyHistory$ReconnectCohort.replayRequests(ProxyHistory.java:232)[199:org.opendaylight.controller.sal-distributed-datastore:1.5.0.SNAPSHOT]
at org.opendaylight.controller.cluster.databroker.actors.dds.AbstractClientHistory$1.replayRequests(AbstractClientHistory.java:311)[199:org.opendaylight.controller.sal-distributed-datastore:1.5.0.SNAPSHOT]
at org.opendaylight.controller.cluster.databroker.actors.dds.AbstractDataStoreClientBehavior.lambda$connectionUp$0(AbstractDataStoreClientBehavior.java:147)[199:org.opendaylight.controller.sal-distributed-datastore:1.5.0.SNAPSHOT]
at org.opendaylight.controller.cluster.access.client.ClientActorBehavior.backendConnectFinished(ClientActorBehavior.java:293)[197:org.opendaylight.controller.cds-access-client:1.1.0.SNAPSHOT]