notify_credentials command
In this PR we are removing a management command that has performance issues and duplicates logic not available in the notify_credentials management command.
BackPopulate Program Credentials job performs data for all the programs
and for all the available learners which takes a lot of time.
Adding in custom arguments will help run this job for specific learners
and specific programs.
* INCR-250: Make compatible with Python 3.x without breaking Python 2.7 support --> openedx/core/djangoapps/programs
* INCR-250: Disable pylint warning and replace _f placeholder with actual name
* INCR-250: pylint format correction and fix over length line limit
