FIO-7854: revert memory leak backport

[brendanbond]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-7854

Description

This PR reverts the 'm' branch (orphaned original 5.x rewrite of the renderer) memory leak backports, because they were causing some problems.

Dependencies

n/a

How has this PR been tested?

n/a

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above

[travist]

I don't want to pull in this revert. From the memory leak PR, there was an issue identified with the PDF builder, and this was resolved with this PR #5729. You will notice that change is part of the revert, but for the most part, MOST of these changes we DO want. My preference is to tackle each issue independently instead of reverting a big change that did make some memory leak improvements.