Fix feature flags .enabled? check

What does this MR do?

Fix feature flags .enabled? check by simplifying the logic and making it more readable.

The current implementation of feature && feature['state'] == 'on' || feature['state'] == 'conditional' && scopes.present? && enabled_scope?(feature['gates'], scopes) is incorrect. For example, if enabled_scope?(feature['gates'], scopes) returns false, we want the statement to return false but currently, it returns true:

2.7.2 :006 > true && true || false && true && false
 => true

Screenshots (strongly suggested)

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

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