fix(rust/rbac-registration): Fix some RBAC logging

[stanislav-tkach]

Description

• Fix (some) logging (use Display instead of Debug for hashes).
• Remove verbose logging in RegistrationChain::new and RegistrationChain::update functions.

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 364/364}$ | ${\color{red}Fail: 0/364}$ |

[stevenj]

Would be helpful to see some "before" and "after" samples showing how these changes affect the output.