authccl: investigate why TestAuthenticationAndHBARules does not work with a shared process virtual cluster

**Describe the problem**

When running the test with a shared process virtual cluster:
```
expected:
ERROR: JWT authentication: not enabled (SQLSTATE 28000)

found:
ERROR: password authentication failed for user jwt_user (SQLSTATE 28P01)
--- FAIL: TestAuthenticationAndHBARules/insecure=false/jwt/enable_jwt_auth (0.01s)
```

**How to reproduce**

Set the following in `TestServerArgs` to force a shared process tenant and cause the failure to happen.
```
DefaultTestTenant: base.SharedTestTenantAlwaysEnabled,
```

**Expected behavior**
The test should pass when running with a shared process virtual cluster, unless after investigation the test is expected not to work with one.

Ref: https://github.com/cockroachdb/cockroach/issues/112857
Epic CRDB-38970

Jira issue: CRDB-32687