Fix flaky order-dependent spec remote_development_agent_config_spec.rb

Issue: Flaky test: ee/spec/models/remote_development/r... (#416411 - closed)

What does this MR do and why?

Fixes an apparently flaky spec which was just discovered, was first merged over a month ago.

See more details here:

• Internal slack thread: https://gitlab.slack.com/archives/CJHPLRTRD/p1687834145825419
• MR thread: !124398 (comment 1446547324)

How to set up and validate locally

RUn ee/spec/models/remote_development/remote_development_agent_config_spec.rb locally and verify it does not fail.

MR acceptance checklist

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