core/db: Revert Patch Added In Attempt To Improve I/O Performance

Reverting the patch since it was causing a regression and after fixing the
regression, there were no performance gains.  At least based on my method
for measurement.

ASTERISK-24050

Review: https://reviewboard.asterisk.org/r/3841/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@419504 f38db490-d61c-443f-a65b-d21fe96a405b