Cleanup: drop KlibIrVersion

Review: https://jetbrains.team/p/kt/reviews/8401
In scope of: KT-55082

Because this version isn't used for anything. We have KotlinAbiVersion
to version the IR format.

compiler/tests-common/tests/org/jetbrains/kotlin/klib/AbstractKlibTextTestCase.kt

@@ -10,7 +10,6 @@ import com.intellij.psi.PsiElement
 import junit.framework.TestCase
 import org.jetbrains.kotlin.backend.common.serialization.CompatibilityMode
 import org.jetbrains.kotlin.backend.common.serialization.DeserializationStrategy
-import org.jetbrains.kotlin.backend.common.serialization.KlibIrVersion
 import org.jetbrains.kotlin.backend.common.serialization.linkerissues.checkNoUnboundSymbols
 import org.jetbrains.kotlin.backend.common.serialization.metadata.KlibMetadataIncrementalSerializer
 import org.jetbrains.kotlin.backend.common.serialization.metadata.makeSerializedKlibMetadata
@@ -193,7 +192,6 @@ abstract class AbstractKlibTextTestCase : CodegenTestCase() {
             libraryVersion = null,
             compilerVersion = KotlinCompilerVersion.VERSION,
             metadataVersion = KlibMetadataVersion.INSTANCE.toString(),
-            irVersion = KlibIrVersion.INSTANCE.toString()
         )
 
         val klibDir = org.jetbrains.kotlin.konan.file.createTempDir("testKlib")

compiler/tests-common/tests/org/jetbrains/kotlin/test/KlibTestUtil.kt

@@ -95,7 +95,6 @@ object KlibTestUtil {
                 compilerVersion = null,
                 abiVersion = null,
                 metadataVersion = KlibMetadataVersion.INSTANCE.toString(),
-                irVersion = null
             ),
             builtInsPlatform = BuiltInsPlatform.COMMON,
             nativeTargets = emptyList(),