chore(cleanup): Adjust for core changes to abstract away the Document type

[Josh-Matsuoka]

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Fixes: https://github.com/cryostatio/cryostat-core/issues/300

Related To: https://github.com/cryostatio/cryostat-core/pull/389

Description of the change:

Adjusts the S3TemplateService and API handlers to account for proposed changes to the TemplateService to avoid directly exposing the Document type.

The S3TemplateService still knows about the Document type and uses it since that's its' implementation, however it does not expose it to callers of getXML.

Motivation for the change:

This change is helpful because users may want to...

How to manually test:

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

Tested with ./mvnw run:quarkus-dev and testing the event template functionality/starting recordings with templates.

[andrewazores]

/build_test

[github-actions[bot]]

Workflow started at 5/21/2024, 1:52:40 PM. View Actions Run.

[github-actions[bot]]

No OpenAPI schema changes detected.

[github-actions[bot]]

No GraphQL schema changes detected.

[github-actions[bot]]

CI build and push: All tests pass ✅ (JDK17) https://github.com/cryostatio/cryostat3/actions/runs/9179129876