Machine Config Operator stuck in progressing state due to PDB restrictions

Issue

• The nodes can't drain due to PodDisruptionBudget (PDB) restrictions.

• This leads to the upgrade process getting stuck and causing degradation in the Machine Config Operator (MCO):

  $ oc get co
  NAME                                       VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
  authentication                             4.14.27   True        False         False      2y
  ...<output ommitted>
  machine-config                             4.13.42   False       True          False      2y 
  ...<output ommitted>