The totally useless health notifications you are getting are from the companion app on the watch, not the phone app. You should be able to turn them off in the Wear app. Watch settings/notifications/choose which apps are allowed to send notifications. Scrolling down the list of apps, you will see two health apps, slide off notifications from the one that says "installed on watch".
Let me be clear here, this is a design flaw and needs a fix immediately. And the so-called solution from @realaud will not be working given that the available settings for a Galaxy Watch 4 and Galaxy Watch 7 would differ in EVERY ASPECT.
I'm confident with that because I have disabled the notification from the Wear app on DAY ONE and here are the results:
1. Heath App ON WATCH still has notification permission
2. It can still send me those stupid notifications at 12am midnight about the "daily activity targets" which you will not be allowed to unset
