chore(templates): remove auth token download flow

[andrewazores]

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Related to cryostatio/cryostat#290
Depends on cryostatio/cryostat#290

Description of the change:

Removes the old API v2.1 auth token download flow in the middle of the event template download action. In 3.0 the client can simply request the file.

Motivation for the change:

This enables the "Events -> Event Templates -> SomeTemplate -> Download" feature to work again with 3.0.

How to manually test:

1. Run CRYOSTAT_IMAGE=quay.io... sh smoketest.sh...
2. ...

[github-actions]

This PR/issue depends on:

• feat(eventtemplates): custom event templates in S3 cryostat#290
  By Dependent Issues (🤖). Happy coding!

[andrewazores]

/build_test

[github-actions]

Test image available:

CRYOSTAT_IMAGE=ghcr.io/cryostatio/cryostat-web:pr-1215-c5b864082901c3600dea8e4b95182d2f2e050ee3 bash smoketest.bash # then open http://localhost:8080

[aali309]

Looks good.

[andrewazores]

Accidentally deleted branch before merging...