Bump ORCA version to 2.55.15
Bump ORCA version to 2.55.15

Signed-off-by: Abhijit Subramanya <53f38ff1dce97d19d07cddf5d958aad389b7c613@pivotal.io>

adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,lisakowen/gpdb,greenplum-db/gporca,greenplum-db/gpdb,lisakowen/gpdb,50wu/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,adam8157/gpdb,jmcatamney/gpdb,xinzweb/gpdb,xinzweb/gpdb,lisakowen/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,lisakowen/gpdb,greenplum-db/gporca,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,50wu/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,adam8157/gpdb,jmcatamney/gpdb,greenplum-db/gporca,adam8157/gpdb,adam8157/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,adam8157/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gporca,greenplum-db/gpdb,jmcatamney/gpdb,50wu/gpdb,adam8157/gpdb,jmcatamney/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,lisakowen/gpdb,jmcatamney/gpdb,50wu/gpdb