Remove .com check in storage alert helper

What does this MR do?

This MR removes the .com checks (::Gitlab.dev_env_or_com?) from ee/app/helpers/ee/namespace_storage_limit_alert_helper.rb. These types of checks are not as favorable as having app settings to gate functionality. Since we already have app settings in these places already, we can remove these .com checks.

I chose not to add a changelog for this MR as it seems more like a refactor to me, but let me know if you disagree.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related to #273048