Bug: when feature is evaluated false, it should return disabled variant

[sjaanus]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Currently, when feature is evaluated false, it is still returning a variant from feature, but should return disabled variant.
Also added client specification test for it Unleash/client-specification#57

To reproduce

1. Update client-specification to 4.2.3 and run tests, which will fail

Sample code (optional)

No response

Version

1.12.1

Expected behavior

Feature should return disabled variant, when feature is evaluated false

Logs (optional)

No response

Additional context (optional)

I am working on the fix, just putting up issue for documentation