Improve MariaDB detection

[swissspidy]

To-do: correctly set WP_CLI_TEST_DBTYPE=mariadb in https://github.com/wp-cli/.github

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/Context/FeatureContext.php	0.00%	12 Missing ⚠️

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[mrsdizzie]

All tests passing now. This requires the latest version of wp-cli/wp-cli#6072

I temporarily updated composer.json here but that probably needs to be undone before merging.

I added $this->variables['MYSQL_BINARY'] = $mysql_binary; to be used in behat tests (examples in the linked pr).