MR Analytics: Add pipelines sanity check

What does this MR do and why?

As described in #342911 (closed), the throughput table on the MR Analytics page occasionally won't be show up. This is due to a JS error as we have a few references to the sub-properties of the pipelines object that can be null. This MR implements a sanity check for the pipelines object.

Screenshots or screen recordings

N/A

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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Related to #342911 (closed)