Bradford Blackmon replaced Barbara Blackmon without retiring Barbara

[alexkost819]

Found by @nozavroni and documented here: #3688 (comment) :

While debugging this, I noticed the file is named data/ms/legislature/Barbara-Blackmon-3b2b3cb2-3ef8-400d-b395-6b0895ea7631.yml but its contents are for Bradford Blackmon, who took SD 21 starting 2024-01-02. "Barbara Blackmon" is also still listed in other_names. It looks like the record was repurposed when Barbara (Bradford's mother, longtime senator) left the seat — but no separate retired entry was created for her, so a search for "Bradford Blackmon" in the repo misses this file entirely.

I left the filename and other_names alone in this PR since the right remediation isn't clear-cut. Let me know how you'd like me to proceed and I'll open the follow-up:

1. Just rename the file to Bradford-Blackmon-...yml and drop "Barbara Blackmon" from other_names. Barbara's history is then lost.
2. Same as (1), plus create a separate retired YAML for Barbara with her service history. (I don't have her full term history handy but could reconstruct from MS Senate records.)
3. Leave as-is; the rename has knock-on effects you'd rather avoid.
4. Something else.

I think #2 makes the most sense. We should have a history of retired legislators (Barbara) and active legislators (her son).