Cleanup: drop KlibIrVersion

Review: https://jetbrains.team/p/kt/reviews/8401
In scope of: KT-55082

Because this version isn't used for anything. We have KotlinAbiVersion
to version the IR format.

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/klib.kt

@@ -703,7 +703,6 @@ fun serializeModuleIntoKlib(
         libraryVersion = null,
         compilerVersion = KotlinCompilerVersion.VERSION,
         metadataVersion = KlibMetadataVersion.INSTANCE.toString(),
-        irVersion = KlibIrVersion.INSTANCE.toString()
     )
 
     val properties = Properties().also { p ->