[Java Client] Remove invalid call to Thread.currentThread().interrupt…

…(); (apache#12652)

- Thread.currentThread().interrupt() shouldn't be called here.
  - it must only be called when handling an InterruptedException.
  - this looks like a copy-paste bug introduced in
    https://github.com/apache/pulsar/pull/731/files#diff-d6fcf8aa2d0035cc386dca0942a452343d6854763c7fd397efa4e660c0069767R1183

pulsar-client/src/main/java/org/apache/pulsar/client/impl/ProducerImpl.java

@@ -1799,7 +1799,6 @@ private void batchMessageAndSend() {
                     processOpSendMsg(opSendMsg);
                 }
             } catch (PulsarClientException e) {
-                Thread.currentThread().interrupt();
                 semaphoreRelease(batchMessageContainer.getNumMessagesInBatch());
             } catch (Throwable t) {
                 semaphoreRelease(batchMessageContainer.getNumMessagesInBatch());