FIO-8684: Fixes cannot attach more than one component to the PDF form

[mikekotikov]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-8684

Description

What changed?

Fixed the issue when PDF form was fully remounted to DOM on every component add. This caused a behavior when iframe ref was lost and only one component could be added to the PDF form.

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Breaking Changes / Backwards Compatibility

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Dependencies

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How has this PR been tested?

Manually. Tried different approaches on writing an automated test for it, but ran into many issues and wasn't been able to complete it.

Checklist:

• I have completed the above PR template
• 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