Minor, remove duplicate test

There's already a test that checks exactly this behavior at
box/oldLanguageVersions/platformTypes/primitives/equalsNull_lv11.kt.

compiler/testData/codegen/box/platformTypes/primitives/equalsNull_withExplicitFlag.kt

@@ -1,45 +0,0 @@
-// IGNORE_BACKEND_FIR: JVM_IR
-// KOTLIN_CONFIGURATION_FLAGS: +JVM.NO_EXCEPTION_ON_EXPLICIT_EQUALS_FOR_BOXED_NULL
-// TARGET_BACKEND: JVM
-// WITH_RUNTIME
-// FILE: equalsNull_withExplicitFlag.kt
-
-// IGNORE_BACKEND: JVM_IR
-// JVM_IR supports behavior since Kotlin 1.3,
-// and '-Xno-exception-on-explicit-equals-for-boxed-null' is a fallback flag introduced in 1.2.
-
-import kotlin.test.*
-
-fun box(): String {
-    assertEquals(J.BOOL_NULL.equals(null), true)
-    assertEquals(J.CHAR_NULL.equals(null), true)
-    assertEquals(J.BYTE_NULL.equals(null), true)
-    assertEquals(J.SHORT_NULL.equals(null), true)
-    assertEquals(J.INT_NULL.equals(null), true)
-    assertEquals(J.LONG_NULL.equals(null), true)
-    assertEquals(J.FLOAT_NULL.equals(null), true)
-    assertEquals(J.DOUBLE_NULL.equals(null), true)
-
-    assertEquals(J.BOOL_NULL == null, true)
-    assertEquals(J.CHAR_NULL == null, true)
-    assertEquals(J.BYTE_NULL == null, true)
-    assertEquals(J.SHORT_NULL == null, true)
-    assertEquals(J.INT_NULL == null, true)
-    assertEquals(J.LONG_NULL == null, true)
-    assertEquals(J.FLOAT_NULL == null, true)
-    assertEquals(J.DOUBLE_NULL == null, true)    
-    
-    return "OK"
-}
-
-// FILE: J.java
-public class J {
-    public static Boolean BOOL_NULL = null;
-    public static Character CHAR_NULL = null;
-    public static Byte BYTE_NULL = null;
-    public static Short SHORT_NULL = null;
-    public static Integer INT_NULL = null;
-    public static Long LONG_NULL = null;
-    public static Float FLOAT_NULL = null;
-    public static Double DOUBLE_NULL = null;
-}

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -18738,11 +18738,6 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull.kt");
             }
 
-            @TestMetadata("equalsNull_withExplicitFlag.kt")
-            public void testEqualsNull_withExplicitFlag() throws Exception {
-                runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull_withExplicitFlag.kt");
-            }
-
             @TestMetadata("hashCode.kt")
             public void testHashCode() throws Exception {
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/hashCode.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -18738,11 +18738,6 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull.kt");
             }
 
-            @TestMetadata("equalsNull_withExplicitFlag.kt")
-            public void testEqualsNull_withExplicitFlag() throws Exception {
-                runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull_withExplicitFlag.kt");
-            }
-
             @TestMetadata("hashCode.kt")
             public void testHashCode() throws Exception {
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/hashCode.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java

@@ -17242,11 +17242,6 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull.kt");
             }
 
-            @TestMetadata("equalsNull_withExplicitFlag.kt")
-            public void testEqualsNull_withExplicitFlag() throws Exception {
-                runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull_withExplicitFlag.kt");
-            }
-
             @TestMetadata("hashCode.kt")
             public void testHashCode() throws Exception {
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/hashCode.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -17242,11 +17242,6 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull.kt");
             }
 
-            @TestMetadata("equalsNull_withExplicitFlag.kt")
-            public void testEqualsNull_withExplicitFlag() throws Exception {
-                runTest("compiler/testData/codegen/box/platformTypes/primitives/equalsNull_withExplicitFlag.kt");
-            }
-
             @TestMetadata("hashCode.kt")
             public void testHashCode() throws Exception {
                 runTest("compiler/testData/codegen/box/platformTypes/primitives/hashCode.kt");