Revert "Fix crash by passing original slot id to avoid race condition."

This reverts commit 33fae77e.

Reason for revert: Initial patch is untested and very dangerous, instead of crashing we are now allowing to return any unused slot (0 being the default value of the static memory).
We decided to revert in order to have an actionnable crash instead of a silent error that use slot

Bug: 316684925
Change-Id: Ia47602329803e8671df90dd95cb4e16956ef64f7
Test: None
Flag: EXEMPT Revert