Block auto-registration is skipped when switching databases

[desertaxle]

First check

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Bug summary

A community user reported that changing the database that backed their local Orion instance resulted in block disappearing from their UI. The user resolved the issue by deleting their .prefect folder.

Thread: https://prefect-community.slack.com/archives/CL09KU1K7/p1666812855264589

Reproduction

- Start up an Orion server with `prefect orion start`
- View blocks in UI
- Change database with `prefect config set PREFECT_ORION_DATABASE_CONNECTION_URL="new_url"
- View lack of blocks in the UI

Error

No response

Versions

Version:             2.6.4
API version:         0.8.2
Python version:      3.10.6
Git commit:          51e92dda
Built:               Thu, Oct 20, 2022 3:11 PM
OS/Arch:             darwin/x86_64
Profile:             local
Server type:         ephemeral
Server:
  Database:          sqlite
  SQLite version:    3.39.3

Additional context

This is likely due to block auto-registration memoization. Memoization should be updated so that the block auto-registration memostore key is no longer valid when the orion database URL is changed.