fix: remove conflicting 400.2 test case from .feature files

[mohdfarhanakram]

What type of PR is this?

correction

What this PR does / why we need it:

Removes the 400.2_empty_request_body test case from both .feature files. This test conflicts with 422.1_missing_phone_number — both send {} as the request body with the same token context but expect different responses (400 vs 422).

Since phoneNumber is the only field in CreateCallForwardingSignal and it is optional, {} is a schema-valid body. The correct error for a missing phone number that cannot be derived from the access token is 422 MISSING_IDENTIFIER, not 400 INVALID_ARGUMENT.

Which issue(s) this PR fixes:

Fixes #218

Special notes for reviewers:

As suggested by @FabrizioMoggio in the issue discussion.

Changelog input

Removed conflicting 400.2_empty_request_body test case from both .feature files. The case is already covered by 422.1_missing_phone_number.

Additional documentation

N/A

[bigludo7]

Good catch !
Thanks !!