Fix timeouts for ES 8 in Pipelines

What does this MR do and why?

Related to #471622 (closed)

This MR fixes timeouts in the Elasticsearch 8 CI pipelines specifically.

The timeouts appear to be due to low diskspace on the runners, but manifest as a pipeline timeout.

The Elasticsearch cluster blocks when creating indices and stalls the pipeline for > 1 hour.

Changes are:

1. fix the environment variable for Elasticsearch 8 services in CI to set cluster.routing.allocation.disk.threshold_enabled to false (there was an extra _)
2. set the timeout for the application setting config to 30 second if run in Rails test environment

MR acceptance checklist

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Screenshots or screen recordings

N/A

How to set up and validate locally

Pipelines should pass