Remove an unneeded column-cache flush in aggregate SELECT
and an unreachable branch in the INSERT logic.
Make sure errors encountered while initializing extensions such as FTS4
get reported out from sqlite3_open().  This fixes a bug introduced by
check-in [9d347f547e7ba9].  Also remove lots of forgotten "breakpoint"
commands left in test scripts over the years.
Do not inject OOM faults into SQLITE_FCNTL_COMMIT_PHASE_TWO file-control invocations. It causes problems for test scripts.