fix: ZeroDivision error in progress
fix: ZeroDivision error in progress

When list of docs is of same length as list of doctypes to ignore, the
formula would throw ZeroDivision error. It's meaningless to subtract
these two quantities hence removed it.

Showing accurate progress bar would require pre-computing number of docs
to be cancelled, which is unnecessary.

Related issue: ISS-20-21-10442

almeidapaulopt/frappe,frappe/frappe,frappe/frappe,almeidapaulopt/frappe,yashodhank/frappe,yashodhank/frappe,frappe/frappe,yashodhank/frappe,almeidapaulopt/frappe,mhbu50/frappe,mhbu50/frappe,almeidapaulopt/frappe,StrellaGroup/frappe,saurabh6790/frappe,mhbu50/frappe,mhbu50/frappe,StrellaGroup/frappe,saurabh6790/frappe,yashodhank/frappe,StrellaGroup/frappe,saurabh6790/frappe,saurabh6790/frappe