Improve error message when electric is unable to obtain initial locks

[AntonOfTheWoods]

In the case where electric is unable to obtain a lock to perform the required config on tables for setting up shapes, it appears* we only get the following messages:

05:37:36.459 [error] ** (Plug.Conn.WrapperError) ** (ArgumentError) cannot fetch key "handle" from conn.query_params because they were not fetche
d. Call Plug.Conn.fetch_query_params/2, either as a plug or directly, to fetch it                                                                
    (plug 1.16.1) lib/plug/conn/unfetched.ex:35: Plug.Conn.Unfetched.raise_unfetched/3                                                           
    (elixir 1.17.2) lib/access.ex:322: Access.get/3  
...

I eventually tracked this down to an incorrectly configured connection elsewhere in my stack that was not releasing locks, but it would have made things much easier to diagnose if this message had have been more expressive.

* I was unable to properly verify whether an initial useful message was emitted, as the logs were overwhelmed with uninformative entries