FIO-9874: fixed an issue where operands disappear

[KatrinKhilko]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-9874

Description

The issue were caused by using wrong instance. Disappearing operands are nested inside columns component that has modelType = 'none', having two columns component within the form caused path collision. Added condition to use fullpath (that is unique) to set the exact instance.

Breaking Changes / Backwards Compatibility

n/a

Dependencies

n/a

How has this PR been tested?

tested manually, all existing tests pass locally

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