RHEL: system hangs at boot and shows critical services failure

Issue

• On systems with SELinux enabled in either Permissive or Enforcing mode, the following messages are seen on the console and prompt is never reached

       Starting Login Service...
  [  OK  ] Started D-Bus System Message Bus.
  ... <Hang of the boot here> ...
  [FAILED] Failed to start Authorization Manager.
  See 'systemctl status polkit.service' for details.
  ...
  [FAILED] Failed to start Login Service.
  See 'systemctl status systemd-logind.service' for details.
  ...
  

• On systems with SELinux disabled (e.g. boot with selinux=0), the following messages are seen on the console then prompt is reached

       Starting Login Service...
  [  OK  ] Started D-Bus System Message Bus.
  ... <Hang of the boot here> ...
  [FAILED] Failed to start Authorization Manager.
  See 'systemctl status polkit.service' for details.
  ...
  [FAILED] Failed to start Login Service.
  See 'systemctl status systemd-logind.service' for details.
  ...
  
  Kernel 3.10.0-1160.11.1.el7.x86_64 on an x86_64
  
  <HOSTNAME> login:
  

• Command systemctl status polkit shows the service is failing for no obvious reason

  [...] systemd[1]: Starting Authorization Manager...
  [...] systemd[1]: polkit.service: main process exited, code=exited, status=1/FAILURE
  [...] systemd[1]: Failed to start Authorization Manager.
  [...] systemd[1]: Unit polkit.service entered failed state.
  [...] systemd[1]: polkit.service failed.
  

• On system with Graphical User Interface, the GDM greeter doesn't show up, a blinking cursor is seen instead