Skip stale-doc validation in ballot question sync

[tripledoublev]

The problem

syncBallotQuestions was failing on dev with a runtypes validation error.

Description of that problem

The script reads each existing Firestore doc and runs it through BallotQuestion.checkWithDefaults before the upsert — so it had to validate data it then overwrites. After commit 79026eb6 narrowed supportCommittee/opposeCommittee from Array(String) to Union(String, Null), any pre-existing dev doc still holding the array shape blew up validation, and the sync exited before writing anything. The script couldn't repair the very state it was designed to repair.

Changes in this PR

The script only consumes four fields off the existing snapshot (testimonyCount, endorseCount, neutralCount, opposeCount) to preserve runtime-owned counters through the upsert. Validating the rest of the doc was incidental. Replaced the BallotQuestion.checkWithDefaults(snap.data()) call with a plain snap.data(). YAML input is still validated on read (line 27).

Test

Reproduced against a local Firestore emulator:

1. Seeded ballotQuestions/23-34 with the broken array shape (supportCommittee: ["Old Committee A", "Old Committee B"]) and non-zero counters.
2. Ran yarn firebase-admin --env=local run-script syncBallotQuestions --dir=... against a single YAML.
3. Sync committed cleanly. Post-state: supportCommittee is now the YAML's string value, opposeCommittee is null, and the four counters were preserved (testimonyCount: 42, endorseCount: 30, etc.).

So one sync run overwrites the stale array shape and self-heals the dev DB without a separate migration.

[LexaMichaelides]

lg, thanks!