Refactor tests to reuse trilogy_test table, remove benchmark script

Address review feedback: use existing trilogy_test columns (date_time_test,
date_test) instead of creating per-test tables for tests that don't need
custom column types. Keeps custom table only for DATETIME(6) and TIME(6)
fractional precision tests.

Remove benchmark script from the committed files.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: schlubbi