You know Russia is a European country right? The place where the government helps athletes take their drugs.
The answer to OP is "extremely common". Just like all sports.
Anyone who doesn't believe that PEDs are common in most sports is delusional. The advantage is just so massive, that it almost self-selects against those who don't use them. Hockey is more skill dependent, than say football, but it's still there.
The testing is also pathetic. You'd have to be totally ignorant of the rules or an idiot to get caught. There's no regular testing in the off season. You could also use naturally occurring PEDs like testosterone, HGH, and insulin, and just stop using them a few weeks before you know you might get tested.
If the NHL were serious, they'd have random testing all year round, including during the off season and when players are on the IR. Star players would get extra scrutiny. Then they'd start handing out 5-10 year or even career bans for infractions. Even then, you'd still be able to use some PEDs. For example, people have wildly different testosterone levels, so you have to set the limit above the highest levels to remove doubt. You could low dose testosterone, to double or triple your own natural testosterone levels, and there's no way to know if that was natural or not.