[ARM] t-server launching a postgres process can result in two t-server processes sometimes

[streddy-yb]

Jira Link: DB-10829
Not sure if I got the Project name right. This was originally reported by @kripasreenivasan. When a universe using an ARM build is upgraded to a newer ARM build, it was observed that Platform health checks were failing. Further investigation showed that there were t-server processes.

Investigation details from @iSignal

The tserver attempted to launch postgres but somehow the launched process shows up as a tserver itself. It is as if only the fork part of the fork + exec worked.

tserver says
I1021 08:11:58.363227 3554572 pg_wrapper.cc:429] PostgreSQL server running as pid 3554620
ps shows
yugabyte 3554572       1 59 Oct21 ?        19:02:45 /home/yugabyte/tserver/bin/yb-tserver --flagfile /home/yugabyte/tserver/conf/server.conf
yugabyte 3554620 3554572  0 Oct21 ?        00:00:07 /home/yugabyte/tserver/bin/yb-tserver --flagfile /home/yugabyte/tserver/conf/server.conf
and no postgres processes
[yugabyte@ip-10-9-100-77 ~]$ ps -ef | grep postg
yugabyte 3807590 3806919  0 16:21 pts/1    00:00:00 grep --color=auto postg

cc @anmalysh-yb @yorq