Investigate increasing number of DOM nodes that are never garbage collected when navigating channels' content

When navigating channels' topics, the number of nodes is always increasing and doesn't seem to be garbage collected for some reason. This looks suspicious since we'd rather expect it to decrease at some point, for example, when a user arrives at a topic that has fewer resources than some of the topics visited earlier and therefore there are fewer elements rendered in the user interface. That never happens, though. This trend can be seen on all performance measurements done in the research phase of https://github.com/learningequality/studio/issues/3363 and could be contributing to memory leaks. The goal of this issue is to find out why is this happening.

Steps to reproduce

Record performance profile while navigating through topics of a channel and notice the rising green line showing a number of nodes in the detailed chart at the bottom.

Acceptance criteria

• Find out why nodes are never garbage collected
• Report results and open issues for resolving discovered problems (new issues don't need to be necessarily resolved in the scope of #3363)

Start by recording a performance profile while navigating through topics of a channel, as described in the reproduction steps, and inspect the rising node count in the detailed chart. Compare the results with the research in issue #3363; done means identifying why nodes are not garbage collected, reporting the findings, and opening follow-up issues for discovered problems.