Remove 9.4 Merge FIXME regarding pm_launch_walreceiver
Remove 9.4 Merge FIXME regarding pm_launch_walreceiver

The pm_launch_walreceiver variable is still needed to handle deadlocks
during parallel segment start. Removing the logic will result in
CAC_STARTUP being received and pg_ctl being stuck waiting for PQPING_OK.
The pm_launch_walreceiver variable is used to send Greenplum-specific
CAC_MIRROR_READY so that pg_ctl can continue.

Relative commit:
https://github.com/greenplum-db/gpdb/commit/b824fe8f269934987e30a4c177605b250703d20f

Co-authored-by: Ekta Khanna <2fbdcb8e3470ad1f53bbeb24e2deced604b8cfa5@pivotal.io>
Co-authored-by: Jimmy Yih <9b5ecfe15c9cd044f4ab483a287130e4bc266a44@pivotal.io>

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