fix: enable functional tests in CI workflow

[geekbrother]

The functional tests are disabled in CI workflow.
The functional_tests flag was disabled due to the tests being out of sync with the latest codebase changes and failing to compile (Issue #195).
Two of the functional tests unexpectedly failed with errors (assuming they are out of sync):

---- functional::multitenant::tenancy::tenant stdout ----
964
thread 'functional::multitenant::tenancy::tenant' panicked at 'Response was not successful', tests/functional/multitenant/tenancy.rs:26:5
....
---- functional::multitenant::fcm::tenant_update_fcm stdout ----
820
thread 'functional::multitenant::fcm::tenant_update_fcm' panicked at 'Response was not successful', tests/functional/multitenant/fcm.rs:40:5

Running of the functional testing should be enabled.