Reduce limit for implicit search too large

Half the limit so that we fail in a bit less than a minute instead of more than 5 minutes.

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -218,7 +218,7 @@ private sealed trait XSettings:
   val Xtarget: Setting[String] = ChoiceSetting("-Xtarget", "target", "Emit bytecode for the specified version of the Java platform. This might produce bytecode that will break at runtime. When on JDK 9+, consider -release as a safer alternative.", ScalaSettings.supportedTargetVersions, "", aliases = List("--Xtarget"))
   val XcheckMacros: Setting[Boolean] = BooleanSetting("-Xcheck-macros", "Check some invariants of macro generated code while expanding macros", aliases = List("--Xcheck-macros"))
   val XmainClass: Setting[String] = StringSetting("-Xmain-class", "path", "Class for manifest's Main-Class entry (only useful with -d <jar>)", "")
-  val XimplicitSearchLimit: Setting[Int] = IntSetting("-Ximplicit-search-limit", "Maximal number of expressions to be generated in an implicit search", 100000)
+  val XimplicitSearchLimit: Setting[Int] = IntSetting("-Ximplicit-search-limit", "Maximal number of expressions to be generated in an implicit search", 50000)
 
   val XmixinForceForwarders = ChoiceSetting(
     name    = "-Xmixin-force-forwarders",