Remove obsolete cron commands

[mlissner]

We used to use pagerank to rank our search results in Solr, but when we moved from a single server to multiple (years ago!), it got harder because application code on one server would generate a ranking file, and then the other server (hosting Solr) would have to load it.

That was fine when our servers were in a data center (shared NFS), but when we moved to AWS, it got harder and I didn't bother figuring it out. It turns out that pagerank isn't great for ranking legal stuff anyway!

But, weirdly, we had code to generate the ranking file, and we had a cronjob calling that code — until now. I just updated k8s to remove the cronjob (sigh), and this PR removes the code for generating the ranking file.

Removals include:

• HTML updates where we mentioned it (these were wrong, but I want to continue calling our relevancy engine CiteGeist, so the name remains).
• A test that we no longer need.
• Removing our dependency on igraph.
• Removing the code to generate pagerank, including some code to deploy it to Solr.

I also slipped in some tweaks to the settings to block a few users. Someday we should make this possible without changes to the code. Someday!

[mlissner]

I just added one more commit to remove two commands related to donations that we don't need anymore. Bye! 👋🏻