Not convinced a symlink provides a safe alternative (https://jira.mariadb.org/browse/MDEV-15526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=121830#comment-121830).
Suggest documentation around overwriting the dependency directives for those service that depend on mysql{,d}.service. The overrides are a simple file dropin as the kb systemd indicates.
I think that the Alias is a standard systemd approach and we shouldn't hack around it with manual symlinks. The problem is that systemd falls back to the SysV script /etc/init.d/mysql. And it will be fixed in MDEV-10797.
> And it will be fixed in MDEV-10797.
Not anytime soon 
. MDEV-10797 has been critical for 1 year to the day, open for 2.5 years, and like MDEV-15526 there is every attempt to treat /etc/init.d/mysql as a feature providing compatibility even though its is really broken on systemd systems. But when those that want /etc/init.d/mysql there aren't willing to consider the lots of watchers on these bugs that hit upgrade bugs because having both is fundamentally incompatible. Attempts to consider what options exist fall into silence and shrug their hands at not understanding systemd, little packaging tests exists, and somehow its all too hard and nothing happens.