community-build: turn off sbt supershell

It adds noise to the community build CI logs.

Author: smarter

community-build/test/scala/dotty/communitybuild/CommunityBuildTest.scala

@@ -103,7 +103,7 @@ final case class SbtCommunityProject(
   override val runCommandsArgs: List[String] =
     // Run the sbt command with the compiler version and sbt plugin set in the build
     val sbtProps = Option(System.getProperty("sbt.ivy.home")) match
-      case Some(ivyHome) => List(s"-Dsbt.ivy.home=$ivyHome")
+      case Some(ivyHome) => List(s"-Dsbt.ivy.home=$ivyHome", "-Dsbt.supershell=false")
       case _ => Nil
     extraSbtArgs ++ sbtProps ++ List(
       "-sbt-version", "1.3.6",