feat(auth): remove auth negotiation and JMX credentials passthrough

[andrewazores]

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Related to cryostatio/cryostat#208

[aali309]

LGTM

[andrewazores]

I should have mentioned - this is also mutually dependent on cryostatio/cryostat#209 since I changed the WebSocket notifications URL. The rest of the changes should work on their own, however, that would be hard to test since the web client will refuse to do anything until it has a WebSocket connection.