db-console: Allow users with MODIFIFYCLUSTERSETTING to view unredacted cluster settings

[kyle-a-wong]

#115851 Introduced logic to allow users with MODIFYCLUSTERSETTING privilege to view sensitive cluster settings when viewing cluster settings via SQL. This same logic doesn't hold true for the cluster settings page in DB-console and sensitive settings are always redacted, unless the user is an admin. Based on this conversations, DB-console should have the same rules and should allow users with MODIFYCLUSTERSETTING to be able to view sensitive cluster settings.

The reason why db-console doesn't show sensitive cluster setting values is because it implements its own authorization and redaction logic and accesses settings via the settings registry directly, instead of querying the crdb_internal table. Possible solutions:

1. Update the admin server to query crdb_internal, which will take care of privilege checking
2. Update the auth checking to allow users with MODIFYCLUSTERSETTING to view sensitive settings

slack conversation for some more context: https://cockroachlabs.slack.com/archives/C063CP41TG9/p1734041508464959
Jira issue: CRDB-45709