[FIX][Benchmarks] RumAuto scenario networking improvements

[sbarrio]

What does this PR do?

This PR introduces 2 improvements to the rumAuto scenario on the benchmark app, both aimed to improve the reliability and stability of synthetics run executing this scenario:

• Addition of a request queue, enforcing a single request at a time and a configurable delay between requests to avoid getting 429'd by the test API.
• The addition of fetchByIds function to perform a single request with a payload of multiple ids instead of performing a request per id when fetching characters, episodes and locations.

Motivation

The RUM Auto scenario test runs are very flimsy and unreliable due to the request rate limits imposed by the test API.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)
• If this PR is auto-generated, please make sure also to manually update the code related to the change