Red Hat Satellite upgrade to 6.9 fails with error 'Following repositories are not available on your system: rhel-7-server-satellite-6.9-rpms'

Issue

• Red Hat Satellite 6.9 upgrade is getting failed with below error:

  Validate availability of repositories:
  \ Some repositories missing, calling `subscription-manager refresh`   [FAIL]
  Following repositories are not available on your system: rhel-7-server-satellite-6.9-rpms
  Scenario [Checks before upgrading to Satellite 6.9] failed.
  
  The following steps ended up in failing state:
  
   [repositories-validate]