chore(core): remove client comment feature flag (#13034)

#### PR Dependency Tree


* **PR #13034** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Refactor**
  * Removed the comment feature flag from the application.
* The ability to enable comments now depends solely on server
configuration, not on a feature flag.
* **Chores**
* Cleaned up related feature flag definitions and internal logic for
comment enablement.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Co-authored-by: fengmk2 <fengmk2@gmail.com>

packages/frontend/core/src/modules/feature-flag/constant.ts

@@ -264,14 +264,6 @@ export const AFFINE_FLAGS = {
     configurable: isCanaryBuild,
     defaultState: false,
   },
-  enable_comment: {
-    category: 'blocksuite',
-    bsFlag: 'enable_comment',
-    displayName: 'Enable Comment',
-    description: 'Enable comment',
-    configurable: true,
-    defaultState: isCanaryBuild,
-  },
 } satisfies { [key in string]: FlagInfo };
 
 // oxlint-disable-next-line no-redeclare