Minor improvements to bisect.scala (#18422)

* Fix bisect release flag documentation to use `...`
* Silence rm with `-f` in case out is missing

---------

Co-authored-by: Oron Port <oron.port@dfiant.works>

Author: soronpo

project/scripts/bisect.scala

@@ -35,9 +35,9 @@ val usageMessage = """
   |* --releases <releases-range>
   |    Bisect only releases from the given range (defaults to all releases).
   |    The range format is <first>...<last>, where both <first> and <last> are optional, e.g.
-  |    * 3.1.0-RC1-bin-20210827-427d313-NIGHTLY..3.2.1-RC1-bin-20220716-bb9c8ff-NIGHTLY
-  |    * 3.2.1-RC1-bin-20220620-de3a82c-NIGHTLY..
-  |    * ..3.3.0-RC1-bin-20221124-e25362d-NIGHTLY
+  |    * 3.1.0-RC1-bin-20210827-427d313-NIGHTLY...3.2.1-RC1-bin-20220716-bb9c8ff-NIGHTLY
+  |    * 3.2.1-RC1-bin-20220620-de3a82c-NIGHTLY...
+  |    * ...3.3.0-RC1-bin-20221124-e25362d-NIGHTLY
   |    The ranges are treated as inclusive.
   |
   |* --bootstrapped
@@ -241,7 +241,7 @@ class CommitBisect(validationScript: File, shouldFail: Boolean, bootstrapped: Bo
     val validationCommandStatusModifier = if shouldFail then "! " else "" // invert the process status if failure was expected
     val bisectRunScript = raw"""
       |scalaVersion=$$(sbt "print ${scala3CompilerProject}/version" | tail -n1)
-      |rm -r out
+      |rm -rf out
       |sbt "clean; set every doc := new File(\"unused\"); set scaladoc/Compile/resourceGenerators := (\`${scala3Project}\`/Compile/resourceGenerators).value; ${scala3Project}/publishLocal"
       |${validationCommandStatusModifier}${validationScript.getAbsolutePath} "$$scalaVersion"
     """.stripMargin