Change healthcheck for PHPStan GA workflow

[tomudding]

The PHPStan GA workflow has been failing for some time. I initially thought this was because MariaDB would kill the temporary server which broke our healthcheck. However, the real reason is that the Docker image has been changed and mysqladmin is no longer included, see https://mariadb.org/mariadb-server-docker-official-images-healthcheck-without-mysqladmin/.

This is frustrating to say the least, as this was of course not (clearly) communicated (MariaDB 11.0.1 release notes, which refers to the 11.0.0 release notes where this was not mentioned).

Proposed fix (I have also increased the health retries by two):

                options: --health-cmd="/usr/local/bin/healthcheck.sh --innodb_initialized" --health-interval=10s --health-timeout=5s --health-retries=5

The healthcheck.sh should not need --su-mysql --connect as these are the default options.