GRA-1493: fixed hard coded dns key

[0xdcarns]

Describe your changes

Fixed security issue

Provide Issue ticket number if applicable/not in title

title.

Provide testing steps

• don't set the DNS_KEY env and query a DNS GET request like curl localhost:8081/api/dns/adm/{network}/nodes
  • Ensure you get an unauthorized response
• set the DNS_KEY env var and query the same one, with -H "Authorization:Bearer ", ensure you get a 500 (if no nodes) otherwise a good response

Checklist before requesting a review

• My changes affect only 10 files or less.
• I have performed a self-review of my code and tested it.
• If it is a new feature, I have added thorough tests, my code is <= 1450 lines.
• If it is a bugfix, my code is <= 200 lines.
• My functions are <= 80 lines.
• I have had my code reviewed by a peer.
• My unit tests pass locally.
• Netmaker is awesome.

[theguy951357]

pr steps pass
critical list passes