[Test] Drop convertToIr method from AbstractFirAnalyzerFacade

We are going to use `convertToIr` from `ModuleCompilerAnalyzedOutput`
without an intermediate wrapper.

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/compiler/based/LowLevelFirAnalyzerFacade.kt

@@ -10,11 +10,9 @@ import org.jetbrains.kotlin.analysis.low.level.api.fir.api.LLFirResolveSession
 import org.jetbrains.kotlin.analysis.low.level.api.fir.api.collectDiagnosticsForFile
 import org.jetbrains.kotlin.diagnostics.KtDiagnostic
 import org.jetbrains.kotlin.fir.AbstractFirAnalyzerFacade
-import org.jetbrains.kotlin.fir.backend.Fir2IrCommonMemberStorage
-import org.jetbrains.kotlin.fir.backend.Fir2IrExtensions
-import org.jetbrains.kotlin.fir.backend.Fir2IrResult
-import org.jetbrains.kotlin.fir.backend.IrBuiltInsOverFir
 import org.jetbrains.kotlin.fir.declarations.FirFile
+import org.jetbrains.kotlin.fir.pipeline.FirResult
+import org.jetbrains.kotlin.fir.pipeline.ModuleCompilerAnalyzedOutput
 import org.jetbrains.kotlin.fir.psi
 import org.jetbrains.kotlin.fir.resolve.ScopeSession
 import org.jetbrains.kotlin.psi.KtFile
@@ -28,6 +26,12 @@ open class LowLevelFirAnalyzerFacade(
     override val scopeSession: ScopeSession
         get() = ScopeSession()
 
+    override val result: FirResult
+        get() {
+            val output = ModuleCompilerAnalyzedOutput(firResolveSession.useSiteFirSession, scopeSession, allFirFiles.values.toList())
+            return FirResult(listOf(output))
+        }
+
     private var resolved: Boolean = false
 
     override fun runCheckers(): Map<FirFile, List<KtDiagnostic>> {
@@ -45,12 +49,4 @@ open class LowLevelFirAnalyzerFacade(
     }
 
     override fun runResolution(): List<FirFile> = allFirFiles.values.toList()
-
-    override fun convertToIr(
-        fir2IrExtensions: Fir2IrExtensions,
-        commonMemberStorage: Fir2IrCommonMemberStorage,
-        irBuiltIns: IrBuiltInsOverFir?
-    ): Fir2IrResult = shouldNotBeCalled()
 }
-
-private fun shouldNotBeCalled(): Nothing = error("Should not be called for LL test")