refactor(server): decrypt license with provided aes key (#12570)

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

- **New Features**
  - Added support for a new AES key for license management, improving license encryption and decryption processes.

- **Bug Fixes**
  - Improved error messages and handling when activating expired or invalid licenses.

- **Refactor**
  - Updated license decryption logic to use a fixed AES key instead of deriving one from the workspace ID.
  - Added validation for environment variable values to prevent invalid configurations.

- **Tests**
  - Enhanced license-related tests to cover new key usage and updated error messages.
  - Updated environment variable validation tests with clearer error messages.

- **Chores**
  - Updated environment variable handling for improved consistency.
  - Set production environment variable explicitly in build configuration.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/env.spec.ts

@@ -29,7 +29,7 @@ test('should read NODE_ENV', t => {
     },
     {
       message:
-        'Invalid value "unknown" for environment variable NODE_ENV, expected one of ["development","test","production"]',
+        'Invalid NODE_ENV environment. `unknown` is not a valid NODE_ENV value.',
     }
   );
 });