dotty phase 2: scalafix ExplicitNonNullaryApply (#28949)

* scalafix ExplicitNonNullaryApply prepare

+ Temporarily use com.sandinh:sbt-scalafix because scalacenter/scalafix#1098
+ Add ExplicitNonNullaryApply rule to .scalafix.conf
+ Manually fix a NonNullaryApply case in DeathWatchSpec that cause
  `fixall` fail because ExplicitNonNullaryApply rule incorrectly rewrite
  `context unbecome` to `context unbecome()` instead of `context.unbecome()`

* scalafix ExplicitNonNullaryApply

fix by enabling only ExplicitNonNullaryApply rule in .scalafix.conf then:
```
% sbt -Dakka.build.scalaVersion=2.13.1
> fixall
```

* scalafmtAll

* Revert to ch.epfl.scala:sbt-scalafix

Co-authored-by: Bùi Việt Thành <thanhbv@sandinh.net>

akka-distributed-data/src/test/scala/akka/cluster/ddata/LocalConcurrencySpec.scala

@@ -64,8 +64,8 @@ class LocalConcurrencySpec(_system: ActorSystem)
   "Updates from same node" must {
 
     "be possible to do from two actors" in {
-      val updater1 = system.actorOf(Props[Updater], "updater1")
-      val updater2 = system.actorOf(Props[Updater], "updater2")
+      val updater1 = system.actorOf(Props[Updater](), "updater1")
+      val updater2 = system.actorOf(Props[Updater](), "updater2")
 
       val numMessages = 100
       for (n <- 1 to numMessages) {