Use MARIADB_ Environment Variable Equivalent for Mariadb

[SamuelMwangiW]

In MariaDB, MARIADB_* environment variables have a higher preference to MYSQL_* variants.

The project only lists the MARIADB_* variants on the Docker hub page. The Knowledge Base also shows a clear bias towards MARIADB_* variants.

MYSQL_* environment variables work with MariaDB and there is no indication that this will change soon. I would therefore understand if you wish to retain MYSQL_* variants.

[github-actions]

Thanks for submitting a PR!

Note that draft PR's are not reviewed. If you would like a review, please mark your pull request as ready for review in the GitHub user interface.

Pull requests that are abandoned in draft may be closed due to inactivity.

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If possible, please consider releasing your code as a package so that the community can still take advantage of your contributions!

If you feel absolutely certain that this code corrects a bug in the framework, please "@" mention me in a follow-up comment with further explanation so that GitHub will send me a notification of your response.