Fix number of media in the bulk optimization

[remyperona]

Description

This PR reverts the bulk optimization method to how it was originally, as the original already managed the next-gen versions correctly.

Type of change

• [x] Bug fix (non-breaking change which fixes an issue).

Checklists

Feature validation

• [x] I triggered all changed lines of code at least once without new errors/warnings/notices.

Code style

• [x] I wrote self-explanatory code about what it does.
• [x] I named variables and functions explicitely.
• [x] I did not introduce unecessary complexity.

[Mai-Saad]

@Tabrisrp Thanks for the PR. Can see the notice 'Hold on ' that images are already optimized also it isnot displayed (like the one here https://github.com/wp-media/imagify-plugin/issues/830) scenario: 1- activate imagify 2- disable optimize with upload 3- upload some images 4- in bulk optimization click imagify all

[remyperona]

Thanks there was a missing change, now it's working, just tested it out on my local