[Gradle, JS] Make default generate kotlin externals as false

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/NpmConstants.kt

@@ -5,4 +5,4 @@
 
 package org.jetbrains.kotlin.gradle.plugin
 
-const val DEFAULT_GENERATE_KOTLIN_EXTERNALS = true
+const val DEFAULT_GENERATE_KOTLIN_EXTERNALS = false

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinProperties.kt

@@ -191,8 +191,8 @@ internal class PropertiesProvider private constructor(private val project: Proje
     /**
      * Generate kotlin/js external declarations from all .d.ts files found in npm modules
      */
-    val jsGenerateExternals: Boolean?
-        get() = booleanProperty("kotlin.js.experimental.generateKotlinExternals")
+    val jsGenerateExternals: Boolean
+        get() = booleanProperty("kotlin.js.generate.externals") ?: DEFAULT_GENERATE_KOTLIN_EXTERNALS
 
     /**
      * Automaticaly discover external .d.ts declarations

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/DefaultKotlinDependencyHandler.kt

@@ -249,7 +249,7 @@ class DefaultKotlinDependencyHandler(
             scope = NpmDependency.Scope.PEER
         )
 
-    private fun defaultGenerateExternals() =
+    private fun defaultGenerateExternals(): Boolean =
         PropertiesProvider(project).jsGenerateExternals
 
     private fun directoryNpmDependency(