Add YnoDeepSubtypes check

See assert in monitoredIsSubtype:

https://github.com/lampepfl/dotty/blob/866656c8d1408697111edf69b0db9b90ce553c5f/compiler/src/dotty/tools/dotc/core/TypeComparer.scala#L216

Author: OlivierBlanvillain

compiler/src/dotty/tools/dotc/core/TypeComparer.scala

@@ -1253,7 +1253,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
       val savedSuccessCount = successCount
       try
         recCount += 1
-        if recCount >= Config.LogPendingSubTypesThreshold then monitored = true
+        if recCount >= Config.LogPendingSubTypesThreshold && !ctx.settings.YnoDeepSubtypes.value then monitored = true
         val result = if monitored then monitoredIsSubType else firstTry
         recCount -= 1
         if !result then