ITS#9494 autogroup: fix db_open trashing thread context

3 jobs for master in 50 minutes and 46 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build
passed build-gnutls-mit-standalone-lloadd #6441

00:47:16

passed build-no-threads-no-slapd #6439

00:03:30

passed build-openssl-heimdal-lloadd #6440

00:49:42