wp-env consistent mysqlPort values

[MichelleBlanchette]

Example:

{
    "core": "WordPress/WordPress#6.6.2",
    "phpVersion": "8.2",
    "plugins": [ "./my-plugin.php" ],
    "port": 80,
    "mysqlPort": 3306,
    "env": {
        "tests": {
            "port": 8000,
            "mysqlPort": 3307
        }
    }
}