Tests: update some backend tests on enum entries

The enumEntriesIntrinsicMultipleEnums.kt test was supposed to check that
JVM backend generates 3 `$EntriesIntrinsicMappings` classes: for X, for
Y, and for Z. Mappings classes are generated for enums without
`entries`, i.e. Kotlin enums compiled without `EnumEntries` language
feature, and Java enums. The test incorrectly _enabled_ the language
feature for X though, and `$EntriesIntrinsicMappings` for X was
generated anyway because of KT-61208.

To keep the original intention of the test, I'm disabling the language
feature for X, so that it will be considered as enum without `entries`.
KT-61208 will be fixed in a separate commit (with separate tests).

The boxInline and bytecodeText tests changed their meaning when language
feature EnumEntries started to be enabled by default, so those changes
are a continuation to ebd43fc8c0. The behavior did not change after
enabling the feature, once again because of KT-61208.

Also, remove obsolete error suppressions which are no longer needed
after 64c8ce18a0.

compiler/testData/codegen/box/enum/enumEntriesIntrinsicMultipleEnums.txt

@@ -2,14 +2,12 @@ Module: lib
 @kotlin.Metadata
 public final enum class X {
     // source: 'X.kt'
-    private synthetic final static field $ENTRIES: kotlin.enums.EnumEntries
     private synthetic final static field $VALUES: X[]
     public final enum static field X1: X
     public final enum static field X2: X
     private synthetic final static method $values(): X[]
     static method <clinit>(): void
     private method <init>(p0: java.lang.String, p1: int): void
-    public static @org.jetbrains.annotations.NotNull method getEntries(): kotlin.enums.EnumEntries
     public static method valueOf(p0: java.lang.String): X
     public static method values(): X[]
 }