remove: overload_mappings tests from ClassDef IR tests

Removed tests for overload_mappings field which was removed as part
of the overload deprecation. ClassDef no longer supports operator
overloading.

- Deleted t/ir/classdef-overload.t entirely (overload-specific)
- Removed overload_mappings subtests from t/ir/classdef-node.t

Fixes test errors: 'Unrecognised parameters for ClassDef constructor:
overload_mappings'

Author: perigrin

t/ir/classdef-node.t

@@ -133,34 +133,4 @@ subtest 'ClassDef to_hash' => sub {
     is($hash->{attributes}{field_count}, 1, 'attributes has field_count');
 };
 
-subtest 'ClassDef with overload_mappings' => sub {
-    require Chalk::IR::Node::ClassDef;
-
-    my $overload_map = {
-        '""'  => 'value',
-        'eq'  => '_string_eq',
-        'cmp' => '_string_cmp',
-    };
-
-    my $classdef = Chalk::IR::Node::ClassDef->new(
-        class_name        => 'Token',
-        overload_mappings => $overload_map,
-    );
-
-    ok(defined($classdef), 'ClassDef with overload_mappings is defined');
-    is(ref($classdef->overload_mappings), 'HASH', 'overload_mappings returns hash');
-    is_deeply($classdef->overload_mappings, $overload_map, 'overload_mappings accessor works');
-};
-
-subtest 'ClassDef overload_mappings defaults to empty hash' => sub {
-    require Chalk::IR::Node::ClassDef;
-
-    my $classdef = Chalk::IR::Node::ClassDef->new(
-        class_name => 'Simple',
-    );
-
-    is(ref($classdef->overload_mappings), 'HASH', 'overload_mappings defaults to hash');
-    is(scalar(keys %{$classdef->overload_mappings}), 0, 'default overload_mappings is empty');
-};
-
 done_testing();