fix(api): Fix location header for archived report generation

[Josh-Matsuoka]

Fixes #762

Hi,

This addresses #762 . The location header that was returned with the request when the cache missed and the report needed to be generated was incorrect, this caused the following sequence of events to happen:

• Client sends report generation request
• Server sees that the report isn't in the cache, kicks off report generation and tries to return an intermediate response to the client
• Location Header on the last step was incorrect causing an exception which returned a 400 to the client despite report generation proceeding as expected.
• Subsequent requests succeeded because at that point the report was cached.

This fixes the location header and adds a missing content type header to active report generation.

[Josh-Matsuoka]

/build_test

[github-actions]

Workflow started at 1/14/2025, 11:44:44 AM. View Actions Run.

[github-actions]

No OpenAPI schema changes detected.

[github-actions]

No GraphQL schema changes detected.

[github-actions]

CI build and push: All tests pass ✅
https://github.com/cryostatio/cryostat/actions/runs/12772345679

[andrewazores]

Could you add some cases to ReportsTest.java to add assertions about these headers?

[andrewazores]

/build_test

[github-actions]

Workflow started at 1/14/2025, 1:40:50 PM. View Actions Run.

[github-actions]

No GraphQL schema changes detected.

[github-actions]

No OpenAPI schema changes detected.

[github-actions]

CI build and push: All tests pass ✅
https://github.com/cryostatio/cryostat/actions/runs/12774254006