IR text tests: Remove useless IGNORE_BACKEND*: JS_IR_ES6 directive

compiler/testData/ir/irText/firProblems/ArrayMap.kt

@@ -1,7 +1,6 @@
 // WITH_STDLIB
 // SKIP_KLIB_TEST
 // IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
 
 // KT-61141: `set()` throws kotlin.IllegalStateException instead of java.lang.IllegalStateException
 // IGNORE_BACKEND: NATIVE

compiler/testData/ir/irText/firProblems/FirBuilder.kt

@@ -1,6 +1,5 @@
 // FIR_IDENTICAL
 // IGNORE_BACKEND_K1: JS_IR
-// IGNORE_BACKEND_K1: JS_IR_ES6
 
 // MODULE: m1
 // FILE: BaseFirBuilder.kt

compiler/testData/ir/irText/firProblems/ImplicitReceiverStack.kt

@@ -2,7 +2,6 @@
 // FULL_JDK
 // JVM_TARGET: 1.8
 // IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
 
 // MUTE_SIGNATURE_COMPARISON_K2: JVM_IR JS_IR NATIVE
 // ^ KT-57788: Fix computing mangled names of types with @EnhancedNullability from IR-based declaration descriptors

compiler/testData/ir/irText/firProblems/kt43342.kt

@@ -1,6 +1,5 @@
 // WITH_STDLIB
 // IGNORE_BACKEND_K2: JS_IR
-// IGNORE_BACKEND_K2: JS_IR_ES6
 // IGNORE_BACKEND_K2: NATIVE
 
 open class ControlFlowInfo<K, V>(val map: Map<K, V>): Map<K, V> by map

compiler/testData/ir/irText/firProblems/lambdaInEnumEntryConstructorCall.kt

@@ -1,5 +1,5 @@
 // WITH_STDLIB
-// IGNORE_BACKEND: JS_IR JS_IR_ES6 NATIVE
+// IGNORE_BACKEND: JS_IR NATIVE
 // ^ KT-61141: absent enum fake_overrides: finalize, getDeclaringClass, clone
 
 class Wrapper(var baseUrl: String)

compiler/testData/ir/irText/firProblems/thisInEnumConstructor.kt

@@ -1,6 +1,5 @@
 // WITH_STDLIB
 // IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
 
 // KT-61141: absent enum fake_overrides: finalize, getDeclaringClass, clone
 // IGNORE_BACKEND: NATIVE

compiler/testData/ir/irText/firProblems/typeVariableAfterBuildMap.kt

@@ -1,6 +1,5 @@
 // WITH_STDLIB
 // IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
 
 // KT-61141: mustCheckInImports throws kotlin.IllegalStateException instead of java.lang.IllegalStateException
 // IGNORE_BACKEND: NATIVE