Optimize KotlinScriptDependenciesClassFinder

Do not call processDirectories for all package prefixes checking inner classes

^KT-39796 Fixed

idea/testData/script/definition/highlighting/nestedClass/lib/lib/KotlinInterface.kt

@@ -0,0 +1,9 @@
+package lib
+
+interface KotlinInterface {
+    interface F {
+        interface I
+    }
+
+    class G
+}

idea/testData/script/definition/highlighting/nestedClass/script.kts

@@ -1,6 +1,6 @@
 import lib.*
 
-fun f(
+fun javaFun(
     <warning>g</warning>: JavaInterface.G,
     <warning>f</warning>: JavaInterface.F,
     <warning>i</warning>: JavaInterface.F.I
@@ -8,4 +8,12 @@ fun f(
 
 }
 
+fun kotlinFun(
+    <warning>g</warning>: KotlinInterface.G,
+    <warning>f</warning>: KotlinInterface.F,
+    <warning>i</warning>: KotlinInterface.F.I
+) {
+
+}
+
 // DEPENDENCIES: classpath:lib-classes; imports:custom.library.*