chore(db): remove migration 0219 to regenerate after staging merge

Drops the 0219_robust_shard SQL, its snapshot, and the journal entry so the
trace-spans/cost schema migration can be regenerated on top of the latest
staging migration chain (avoids a number collision with staging's migrations).

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: icecrasher321