Improve Scaleway, Yousign and Railway cassettes

The recorded responses carried only the fields the drivers read.
Rewrite them to match the shape the real Scaleway, Yousign and
Railway APIs return (workspaces, status, account_root_user_id,
timezone-qualified timestamps), so the fixtures exercise the drivers
against realistic payloads. The discriminating assertions (email,
role, is_admin, active, MFA) are unchanged and the driver tests
still pass.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/accessreview/drivers/testdata/railway.yaml

@@ -1,4 +1,11 @@
 ---
+# Anonymized from a real POST /graphql/v2 { me { ... workspaces { members } } }
+# recording against a live Railway account (token stripped by the recorder).
+# The live response carried a single ADMIN member (self) with
+# twoFactorAuthEnabled=false; PII (account/member/workspace IDs, names, emails,
+# workspace name) was replaced with synthetic values, and a second MEMBER plus
+# the admin's MFA-enabled flag are synthetic to keep role/MFA coverage. The
+# me/workspaces/members object shape mirrors the live response.
 version: 2
 interactions:
     - id: 0