`SHOW CREATE EXTERNAL CONNECTION` does not redact secret keys

**Describe the problem**

Using `SHOW CREATE ALL EXTERNAL CONNECTIONS` noticed that secrets keys for the storage URI are not redacted. Perhaps this is desirable for `root`/`admin`, or the person who created it. Filing this issue to check whether there could be any improvements around this, as per discussion with @adityamaru.

`SHOW CREATE SCHEDULES` seems to redact even for the user who created the schedule.

**To Reproduce**

Create an external connection, and then run `SHOW CREATE EXTERNAL CONNECTION` on that ext conn.

**Expected behavior**

Probably what the general behavior is across all `SHOW CREATE` depending on privileges and such, not sure what the overall policy is here.

Jira issue: CRDB-31937