[BC Idea]: Add Session Event table to retention policy base app allowed tables

BC Idea Link

https://experience.dynamics.com/ideas/idea/?ideaid=949279e1-6e86-f111-9b47-7c1e52b644b5

Description

Issue Description
On the SQL side, this change was already implemented previously, but the BaseApp retention policy install codeunit does not yet include Session Event in its allowed table list.

To keep the AL side aligned with the existing SQL-side behavior, extend the retention policy initialization so that Session Event is added as an allowed table alongside the current system tables.

Expected Result
Retention policy installation in BaseApp adds Session Event to the allowed tables, matching the behavior already established on the SQL side.

Acceptance Criteria

Session Event is added to the BaseApp retention policy allowed tables.
The change follows the same intent as the existing SQL-side implementation.
Existing allowed tables remain unchanged.
Retention policy setup still completes successfully.

I will provide the implementation for this BC Idea

• I will provide the implementation for this BC Idea

Locate the BaseApp retention policy installation codeunit and inspect the current allowed system-table list, then compare its intent with the existing SQL-side implementation mentioned in the issue. Done means Session Event is included, existing allowed tables are unchanged, and retention policy setup still completes successfully.