Description of problem:
Registration of CentOS 8 & RHEL 8 hosts that are already subscribed to another instance (or to cloud) fails with following error:
```
Unregistering from: satellite.example.com
Unable to verify server's identity: [SSL: TLSV1_ALERT_UNKNOWN_CA] tlsv1 alert unknown ca (_ssl.c:897)
```

Version-Release number of selected component (if applicable):
6.10

• CentOS 8 and RHEL 8 only that are already subscribed somewhere else

Steps to Reproduce:
1. Try to register already subscribed CentOS 8 / RHEL 8 machine

Actual results:
Registration fails with error:
```
Unregistering from: satellite.example.com
Unable to verify server's identity: [SSL: TLSV1_ALERT_UNKNOWN_CA] tlsv1 alert unknown ca (_ssl.c:897)
```

Expected results:
Machine successfully registered.

Additional info:
Registration template should run `subscription-manager clean` command when `--force` parameter is `true`