K2: for Java source override, don't compare return types in override checker

#KT-57044 Fixed

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.fir.txt

@@ -0,0 +1,14 @@
+FILE: K.kt
+    public open class K : R|kotlin/Any| {
+        public constructor(): R|K| {
+            super<R|kotlin/Any|>()
+        }
+
+        public open fun test(): R|kotlin/Unit| {
+            ^test Q|kotlin/Unit|
+        }
+
+    }
+    public final fun jk(): R|kotlin/Unit| {
+        R|/JK.JK|().R|/JK.test|()
+    }

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.kt

@@ -0,0 +1,18 @@
+// FILE: JK.java
+
+public class JK extends K {
+    @Override
+    public void test() {
+
+    }
+}
+
+// FILE: K.kt
+
+open class K {
+    open fun test() = Unit
+}
+
+fun jk() {
+    JK().test()
+}

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.fir.txt

@@ -0,0 +1,14 @@
+FILE: K.kt
+    public final fun jk(): R|kotlin/Unit| {
+        ^jk R|/JK.JK|().R|/JK.test|()
+    }
+    public open class K : R|kotlin/Any| {
+        public constructor(): R|K| {
+            super<R|kotlin/Any|>()
+        }
+
+        public open fun test(): R|kotlin/Unit| {
+            ^test Q|kotlin/Unit|
+        }
+
+    }

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.kt

@@ -0,0 +1,16 @@
+// FILE: JK.java
+
+public class JK extends K {
+    @Override
+    public void test() {
+
+    }
+}
+
+// FILE: K.kt
+
+fun jk() = JK().test()
+
+open class K {
+    open fun test() = Unit
+}