Unnecessary overhead due to Jackson serialization in all entities

### Describe the bug

The generic property bags `properties` and `internalProperties` are persisted as strings, which contain the JSON serialized representation of both property bags.

Each time a call site requests any of these property bags, the JSON representation is being parsed.

This behavior is quite expensive.

_How_ entities and their attributes are persisted should really be up to the actual persistence implementation.

### To Reproduce

_No response_

### Actual Behavior

_No response_

### Expected Behavior

_No response_

### Additional context

_No response_

### System information

_No response_

Start by tracing how the properties and internalProperties bags are persisted and where their JSON representations are parsed at call sites. The issue provides no file or test entry point; done would mean avoiding unnecessary Jackson parsing while preserving entity property behavior across the persistence implementation.

Written by the indexing model from the issue text.