Completed payment does not correctly detects waived vs paid scenario

[jardakotesovec]

Describe the bug
From @Tribunal33 :
For 3.5 OJS when I have payments enabled and I move from unpaid or paid, to waived it doesn't seem to save it and goes back to paid when I reload the submission. This doesn't happen on 3.4 as far as I could tell.

Investigation
I tracked it down to the change of the completed_payments amount column type - https://github.com/pkp/ojs/blame/main/classes/migration/install/OJSMigration.php#L418

As result this condition is not working as expected - https://github.com/pkp/ojs/blob/main/classes/components/forms/publication/SubmissionPaymentsForm.php#L53

Just improving this condition might be enough.. but better to properly review impact of this change.

What application are you using?
OJS, OMP or OPS version 3.5

[jardakotesovec]

@touhidurabir Could you have a look?