slapd: delete unused entry_schema_check(oldattrs) parameter

Unused since 2001 2ae02fc1
3 jobs for master in 50 minutes and 7 seconds (queued for 11 minutes and 57 seconds)
Status Name Job ID Coverage
  Build
passed build-gnutls-mit-standalone-lloadd #9568

00:42:14

passed build-no-threads-no-slapd #9566

00:01:47

passed build-openssl-heimdal-lloadd #9567

00:48:19