[K/N][IR] Re-enable string_builder0 and utf8 tests in 2-stage mode

^KT-33175

kotlin-native/backend.native/tests/build.gradle

@@ -2302,8 +2302,6 @@ task moderately_large_array1(type: KonanLocalTest) {
 }
 
 task string_builder0(type: KonanLocalTest) {
-    // Cannot be executed in the two-stage mode due to KT-33175.
-    enabled = !twoStageEnabled
     expectedFail = (project.testTarget == 'wasm32') // Uses exceptions.
     goldValue = "OK\n"
     source = "runtime/text/string_builder0.kt"
@@ -2355,9 +2353,8 @@ task indexof(type: KonanLocalTest) {
 }
 
 task utf8(type: KonanLocalTest) {
-    // Cannot be executed in the two-stage mode due to KT-33175.
     // Uses exceptions so cannot run on wasm.
-    enabled = !twoStageEnabled && (project.testTarget != 'wasm32')
+    enabled = project.testTarget != 'wasm32'
     goldValue = "Hello\nПривет\n\uD800\uDC00\n\n\uFFFD\uFFFD\n\uFFFD12\n\uFFFD12\n12\uFFFD\n\uD83D\uDE25\n\uD83D\uDE25\n"
     source = "runtime/text/utf8.kt"
 }