chore: replace deprecated endpoints for vespa search feeding

[esolitos]

What

• Replace the custom vespa cloud endpoints with the generated ones.

Why

• The custom endpoints are deprecated and will be removed in the future.

Additional Info

Related PRs:

• https://github.com/vespa-engine/documentation/pull/3327
• https://github.com/vespa-engine/sample-apps/pull/1445

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[esolitos]

Closing for now due to incompatibilities.