[MPP] Change the deprecation message for HMPP properties

KT-55891

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/mpp/MppDeprecatedPropertiesIt.kt

@@ -39,7 +39,7 @@ class MppDeprecatedPropertiesIt : KGPBaseTest() {
 
             defaultFlags.keys.forEach { flag ->
                 assert(
-                    warnings.any { warning -> Regex(".*$flag.*is deprecated.*").matches(warning) },
+                    warnings.any { warning -> Regex(".*$flag.*is obsolete.*").matches(warning) },
                     "A deprecation warning for the '$flag' should have been reported",
                 )
             }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/internal/deprecationDiagnostics.kt

@@ -66,4 +66,5 @@ internal val deprecatedMppProperties: List<String> = listOf(
 )
 
 internal fun getMppDeprecationWarningMessageForProperty(property: String): String =
-    "w: The property '$property' is deprecated and is scheduled for removal in the stable Kotlin Multiplatform."
+    "w: The property '$property' is obsolete and will be removed in Kotlin 1.9. Read the details here: " +
+            "https://kotlinlang.org/docs/multiplatform-compatibility-guide.html#deprecate-hmpp-properties"