fix: rewrite database upgrade v201_add_missing_donors callback to prevent memory exhausted issue

[ravinderk]

Bug Report

User Story

As an admin, I want to update plugin old instance ( version <= 1.8.16 ) with latest without any issue.

Current Behavior

Few sites database update process stalled when process v201_add_missing_donors callback if donors are more then 1000.

ref: https://secure.helpscout.net/conversation/670275338/26121?folderId=848135

Bug Type

• This bug describes functionality that once worked as expected in version X.X.X.
• This bug describes functionality that never worked as expected.
• I am not sure whether this functionality ever worked as expected.

Steps to Reproduce

1. I have a dummy database on which I am able to reproduce this issue

Acceptance Criteria

• Upgrade process must run smoothly on dummy database.
• Review donors before and after upgrades.

[ravinderk]

I am fixing this issue in https://github.com/impress-org/give/tree/issue/3797