Tests: Disable two-stage mode for failing tests

Some tests fail due to compiler bugs unrelated to the source
libraries feature (see KT-33160, KT-33175). This patch disables
the two-stage mode for these tests.

backend.native/tests/build.gradle

@@ -2148,6 +2148,8 @@ 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"
@@ -2199,6 +2201,8 @@ task indexof(type: KonanLocalTest) {
 }
 
 task utf8(type: KonanLocalTest) {
+    // Cannot be executed in the two-stage mode due to KT-33175.
+    enabled = !twoStageEnabled
     expectedFail = (project.testTarget == 'wasm32') // Uses exceptions.
     goldValue = "Hello\nПривет\n\uD800\uDC00\n\n\uFFFD\uFFFD\n\uFFFD12\n\uFFFD12\n12\uFFFD\n\uD83D\uDE25\n\uD83D\uDE25\n\uD83D\uDE25\n"
     source = "runtime/text/utf8.kt"
@@ -3446,7 +3450,8 @@ standaloneTest("interop_opengl_teapot") {
 */
 
 interopTest("interop_objc_smoke") {
-    disabled = !isAppleTarget(project)
+    // Cannot be executed in the two-stage mode due to KT-33160.
+    disabled = !isAppleTarget(project) || twoStageEnabled
     goldValue = "84\nFoo\nDeallocated\n" +
             "Hello, World!\nKotlin says: Hello, everybody!\nHello from Kotlin\n2, 1\n" +
             "true\ntrue\n" +