[Frontend] Update existing approvers on yaml update

Why are we doing this work

existingApprovers property in security_orchestration/components/policy_editor/scan_result/editor_component.vue is only updated when edited in rule mode.

It also hast be updated when user edits yaml mode

Relevant links

Non-functional requirements

• Documentation:
• Feature flag: multiple_approval_actions
• Performance:
• Testing:

Implementation plan

Verification steps