Improve database collation detection

[mneudert]

Description:

The collation detection introduced in #22564 can create problems in some environments, most likely for MariaDB 11.4+.

In MariaDB 11.4+ the query SHOW COLLATION WHERE `Default` = "Yes" AND `Charset` = 'utf8mb4' does not return any result, and throwing an exception means a new installation is not possible. Showing the diagnostics page also crashes if no collation is configured.

When updating an existing Matomo installation, the update migration should detect a collation to prevent this problem. However, if there are already mixed tables (e.g. users table with general_ci and archive table with uca1400_ai_ci) this is not something we can be really sure of.

The check is changed to use SHOW CHARACTER SET instead. This should, at least for utf8mb4 character sets, always return a default we can use for installation/diagnostics. For utf8, or if there is no value found, it will now return an empty string. With the updated CREATE DATABASE statement, this should now allow installation for MariaDB 11.4+ again, and also for database setups that are not configured to handle utf8mb4.

Forcing utf8 charset detection during install

• Start a database server, for example MySQL 8.0
• Create a database with utf8mb3

  CREATE DATABASE matomo CHARSET utf8mb3;

• Deactivate innodb_file_per_table for the server:

   SET GLOBAL innodb_file_per_table = OFF;

• Proceed to install Matomo

The configuration should be created as [database] charset = utf8 (missing from config.ini.php because this is the default from global.ini.php), and no collation.

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed