[Wasm] Update testData after adding K2 and new test infra support.

- Actualize muted K2 tests
- Actualize muted K1 tests with module systems because legacy Wasm test
  infra had no respect for "// MODULE: ..." test directives

compiler/testData/codegen/boxWasmJsInterop/externalTypeOperators.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND_K2: WASM
 // WITH_STDLIB
 // FILE: externals.js
 

compiler/testData/codegen/boxWasmJsInterop/vararg.kt

@@ -1,4 +1,5 @@
 // IGNORE_BACKEND_K2: JS_IR
+// IGNORE_BACKEND_K2: WASM
 
 // Partial copy of js/js.translator/testData/box/native/vararg.kt
 // With some additions for concrete number types, strings and function references