Remove build_serializer_config function

app/assets/javascripts/content_editor/services/build_serializer_config.js

-const buildSerializerConfig = (extensions = []) =>
-  extensions
-    .filter(({ serializer }) => serializer)
-    .reduce(
-      (serializers, { serializer, tiptapExtension: { name, type } }) => {
-        const collection = `${type}s`;
-
-        return {
-          ...serializers,
-          [collection]: {
-            ...serializers[collection],
-            [name]: serializer,
-          },
-        };
-      },
-      {
-        nodes: {},
-        marks: {},
-      },
-    );
-
-export default buildSerializerConfig;

spec/frontend/content_editor/services/build_serializer_config_spec.js

-import * as Blockquote from '~/content_editor/extensions/blockquote';
-import * as Bold from '~/content_editor/extensions/bold';
-import * as Dropcursor from '~/content_editor/extensions/dropcursor';
-import * as Paragraph from '~/content_editor/extensions/paragraph';
-
-import buildSerializerConfig from '~/content_editor/services/build_serializer_config';
-
-describe('content_editor/services/build_serializer_config', () => {
-  describe('given one or more content editor extensions', () => {
-    it('creates a serializer config that collects all extension serializers by type', () => {
-      const extensions = [Bold, Blockquote, Paragraph];
-      const serializerConfig = buildSerializerConfig(extensions);
-
-      extensions.forEach(({ tiptapExtension, serializer }) => {
-        const { name, type } = tiptapExtension;
-        expect(serializerConfig[`${type}s`][name]).toBe(serializer);
-      });
-    });
-  });
-
-  describe('given an extension without serializer', () => {
-    it('does not include the extension in the serializer config', () => {
-      const serializerConfig = buildSerializerConfig([Dropcursor]);
-
-      expect(serializerConfig.marks[Dropcursor.tiptapExtension.name]).toBe(undefined);
-      expect(serializerConfig.nodes[Dropcursor.tiptapExtension.name]).toBe(undefined);
-    });
-  });
-
-  describe('given no extensions', () => {
-    it('creates an empty serializer config', () => {
-      expect(buildSerializerConfig()).toStrictEqual({
-        marks: {},
-        nodes: {},
-      });
-    });
-  });
-});