Remove bytecode text test kt15806.kt

It's not correct to expect that the backend generates the `when` in this
test as tableswitch because there are only two branches. JVM IR has a
cutoff in the when optimization and generates `when`s with fewer than 3
branches as if-else chains, which is probably better. Note that there's
also a corresponding box test in when/enumOptimization/, so the backend
behavior is still tested.

compiler/tests-gen/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -4991,11 +4991,6 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/whenEnumOptimization/kt14802.kt");
         }
 
-        @TestMetadata("kt15806.kt")
-        public void testKt15806() throws Exception {
-            runTest("compiler/testData/codegen/bytecodeText/whenEnumOptimization/kt15806.kt");
-        }
-
         @TestMetadata("manyWhensWithinClass.kt")
         public void testManyWhensWithinClass() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/whenEnumOptimization/manyWhensWithinClass.kt");