Fix number of accounts processed counter

Author: katherine-signal

service/src/main/java/org/whispersystems/textsecuregcm/workers/EncryptDeviceCreationTimestampCommand.java

@@ -78,9 +78,10 @@ protected void crawlAccounts(final Flux<Account> accounts) {
                         log.warn("Failed to encrypt creation timestamp on device {}, account {}", device.getId(), account.getUuid(), throwable);
                         return Mono.empty();
                       });
-                }, MAX_CONCURRENCY),
+                }, MAX_CONCURRENCY)
+                .then()
+                .doOnSuccess(_ -> processedAccountCounter.increment()),
             MAX_CONCURRENCY)
-        .doOnComplete(processedAccountCounter::increment)
         .then()
         .block();
   }