Remove tests on -Xuse-ir compiler flag

This flag is going to be removed because old backend is not supported
anymore, therefore there's no need to test it.

libraries/scripting/jvm-host-test/build.gradle.kts

@@ -43,7 +43,6 @@ tasks.withType<org.jetbrains.kotlin.gradle.dsl.KotlinCompile<*>> {
 projectTest(parallel = true) {
     dependsOn(":dist")
     workingDir = rootDir
-    systemProperty("kotlin.script.test.base.compiler.arguments", "-Xuse-old-backend")
 }
 
 // This doesn;t work now due to conflicts between embeddable compiler contents and intellij sdk modules
@@ -54,12 +53,6 @@ projectTest(parallel = true) {
 //    classpath = embeddableTestRuntime
 //}
 
-projectTest(taskName = "testWithIr", parallel = true) {
-    dependsOn(":dist")
-    workingDir = rootDir
-    systemProperty("kotlin.script.base.compiler.arguments", "-Xuse-ir")
-}
-
 projectTest(taskName = "testWithK2", parallel = true) {
     dependsOn(":dist")
     workingDir = rootDir

libraries/scripting/jvm-host-test/test/kotlin/script/experimental/jvmhost/test/ImplicitsFromScriptResultTest.kt

@@ -35,24 +35,19 @@ import kotlin.script.experimental.jvmhost.JvmScriptCompiler
  */
 class ImplicitsFromScriptResultTest : TestCase() {
     fun testImplicits() {
-        if (System.getProperty("kotlin.script.base.compiler.arguments")?.let {
-                !it.contains("-Xuse-ir") || it.contains("-Xuse-old-backend")
-            } == true
-        ) {
-            // the implementation of the Compiler Host doesn't work with IR - the inter-script symbol table
-            // should be maintained to make it run (see latest REPL compiler implementations for details
-            // TODO: consider either fix it or rewrite to the REPL compiler
-            val host = CompilerHost()
+        // the implementation of the Compiler Host doesn't work with IR - the inter-script symbol table
+        // should be maintained to make it run (see latest REPL compiler implementations for details
+        // TODO: consider either fix it or rewrite to the REPL compiler
+        val host = CompilerHost()
 
-            val snippets = listOf(
-                "val xyz0 = 42",
-                "fun f() = xyz0",
-                "val finalRes = xyz0 + f()",
-            )
-            for (snippet in snippets) {
-                val res = host.compile(snippet)
-                assertTrue(res is ResultWithDiagnostics.Success)
-            }
+        val snippets = listOf(
+            "val xyz0 = 42",
+            "fun f() = xyz0",
+            "val finalRes = xyz0 + f()",
+        )
+        for (snippet in snippets) {
+            val res = host.compile(snippet)
+            assertTrue(res is ResultWithDiagnostics.Success)
         }
     }
 }