K2: remove JAVA_SHADOWED_PROTECTED_FIELD_REFERENCE error

This is a partial revert of 949a39b80f. In the end it turned out not
necessary to prohibit this case (and perform a breaking change), because
JVM backend was fixed to generate it correctly in d73d3c46e2.

 #KT-55307 Declined
 #KT-55846 Declined

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -4875,14 +4875,6 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
-    add(FirJvmErrors.JAVA_SHADOWED_PROTECTED_FIELD_REFERENCE) { firDiagnostic ->
-        JavaShadowedProtectedFieldReferenceImpl(
-            firDiagnostic.a,
-            firDiagnostic.b,
-            firDiagnostic as KtPsiDiagnostic,
-            token,
-        )
-    }
     add(FirJsErrors.IMPLEMENTING_FUNCTION_INTERFACE) { firDiagnostic ->
         ImplementingFunctionInterfaceImpl(
             firDiagnostic as KtPsiDiagnostic,

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -3395,12 +3395,6 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = JavaSamInterfaceConstructorReference::class
     }
 
-    abstract class JavaShadowedProtectedFieldReference : KtFirDiagnostic<PsiElement>() {
-        override val diagnosticClass get() = JavaShadowedProtectedFieldReference::class
-        abstract val containerClass: ClassId
-        abstract val shadowingClass: ClassId
-    }
-
     abstract class ImplementingFunctionInterface : KtFirDiagnostic<KtClassOrObject>() {
         override val diagnosticClass get() = ImplementingFunctionInterface::class
     }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -4104,13 +4104,6 @@ internal class JavaSamInterfaceConstructorReferenceImpl(
     override val token: KtLifetimeToken,
 ) : KtFirDiagnostic.JavaSamInterfaceConstructorReference(), KtAbstractFirDiagnostic<PsiElement>
 
-internal class JavaShadowedProtectedFieldReferenceImpl(
-    override val containerClass: ClassId,
-    override val shadowingClass: ClassId,
-    override val firDiagnostic: KtPsiDiagnostic,
-    override val token: KtLifetimeToken,
-) : KtFirDiagnostic.JavaShadowedProtectedFieldReference(), KtAbstractFirDiagnostic<PsiElement>
-
 internal class ImplementingFunctionInterfaceImpl(
     override val firDiagnostic: KtPsiDiagnostic,
     override val token: KtLifetimeToken,