test: fix signature-flow endpoint URL in integration test

Update Behat test to use correct endpoint URL and parameter name:
- Changed from '/api/v1/admin/signature-flow' to '/api/v1/admin/signature-flow/config'
- Changed parameter from 'flow' to 'mode'

This aligns with the actual AdminController endpoint implementation.

Signed-off-by: Vitor Mattos <[email protected]>

Author: vitormattos

tests/integration/features/sign/sequential_signing.feature

@@ -35,8 +35,8 @@ Feature: sequential-signing
   Scenario: Sequential signing - only first signer can sign initially
     Given user "signer1" exists
     And user "signer2" exists
-    And sending "post" to ocs "/apps/libresign/api/v1/admin/signature-flow"
-      | flow | ordered_numeric |
+    And sending "post" to ocs "/apps/libresign/api/v1/admin/signature-flow/config"
+      | mode | ordered_numeric |
     And the response should have a status code 200
     When sending "post" to ocs "/apps/libresign/api/v1/request-signature"
       | file | {"url":"<BASE_URL>/apps/libresign/develop/pdf"} |