Update Notice for Public Schema

[ghislaineguerin]

Description

In Mathesar, the public schema contains a notice: "Every PostgreSQL database includes the 'public' schema. This protected schema can be read by anybody who accesses the database."

Expected behavior

The notice must be updated to reflect changes to public schema in latest PostgreSQL version.

• The CREATE privilege is not granted by default to all users to enhance security.
• The database owner can grant the CREATE privilege if needed.