Description of problem:
When device is managed by NetworkManager but connected externally, doing snapshot and rollback makes the external connection permanent and unused.

Version-Release number of selected component (if applicable):
1.36.0-2.el8

How reproducible:
always

Steps to Reproduce:
1. change lines in libnm_snapshot_reattach_unmanaged_ports_to_bridge setting ports to "managed yes"
2. run the test

Actual results:
After the test, there are connections portXb and portXc.

Expected results:
Connection portXb and portXc should not become persistent.

Additional info:
see "Status After Clean" in this report https://tools.dqe.lab.eng.bos.redhat.com/fpokryvk/reports/report_NetworkManager-ci_Test0_libnm_snapshot_reattach_unmanaged_ports_to_bridge_managed_yes.html