If you really don’t care the easiest hack I’ve seen others do is…
Go to the AYON Deadline Plug-in: Ayon/Ayon.param and open it in notepad.
Find:
[AyonApiKey]
Type=password
Change it to:
[AyonApiKey]
Type=string
You can now configure this key in plain-text without Deadline bitching about any of its security features. If you’re fine with just throwing all the stuff into the env of jobs anyways I guess you’re just as fine with having these plug-in settings for an API key settable in plain text.
It may even work (although I haven’t tried)… to set it to string, set the value, and then change it back to password. I assume it won’t work, but you never know. 
And of course, sharing the Deadline docs for Secrets Management.