Update configuration for MySQL 8

Summary:
Allow to run MySQL 8 on the container.

Fixes the following issues:

• Messages have been moved, so default value is now acceptable
• Failed to access directory for --secure-file-priv
• Allow legacy clients (like PHP or GO default connectors) to connect

Ref T1435

References:

• https://mysqlserverteam.com/mysql-8-0-4-new-default-authentication-plugin-caching_sha2_password/

Test Plan: Live at acquisitariat

Reviewers: dereckson

Reviewed By: dereckson

Subscribers: Nasqueron Docker deployment squad

Tags: Docker images

Maniphest Tasks: T1435

Differential Revision: https://devcentral.nasqueron.org/D1769