[FE 1.0] Make "Unit conversions" accessible experimental feature

kotlin-native/backend.native/tests/debugger/src/test/kotlin/org/jetbrains/kotlin/native/test/debugger/LldbTests.kt

@@ -343,7 +343,7 @@ class LldbTests {
                v()
             }
         """.feedOutput("kt42208-3.kt")
-        val binary = arrayOf(kt42208One, kt42208Two, kt42208Three).binary("kt42208", "-g", "-XXLanguage:+UnitConversion")
+        val binary = arrayOf(kt42208One, kt42208Two, kt42208Three).binary("kt42208", "-g", "-XXLanguage:+UnitConversionsOnArbitraryExpressions")
         """
             > b kt42208-2.kt:5
             > ${lldbCommandRunOrContinue()}