IR text tests: Don't dump signatures for local declarations

1. Local declarations don't participate in IR-linkage, because they
can be referenced only inside the same body -> can be dropped
from IR text tests.

2. Mangled names for private declarations computed by descriptors/fir
are actually not used anywhere (they are recomputed by IR
immediately before serialization of IR). But sometimes such
mangled names diverge between K1 and K2 -> don't check them, but
always check mangled names computed by IR even for private
declarations.

3. Also: Drop DUMP_LOCAL_DECLARATION_SIGNATURES test directive.

^KT-57428 Obsolete
^KT-57430 Obsolete
^KT-57434 Obsolete
^KT-57778 Obsolete
^KT-57775 Obsolete

compiler/testData/ir/irText/classes/enumClassModality.kt

@@ -1,11 +1,5 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-
-// MUTE_SIGNATURE_COMPARISON_K2: ANY
-// ^ KT-57775
-
-// KT-61141: absent enum fake_overrides: finalize, getDeclaringClass, clone
-// IGNORE_BACKEND: NATIVE
+// IGNORE_BACKEND: JS_IR JS_IR_ES6 NATIVE
+// ^ KT-61141: absent enum fake_overrides: finalize (K1), getDeclaringClass (K1), clone (K2)
 
 enum class TestFinalEnum1 {
     X1