Hi @sohel,
It looks like an issue with integration of openmrs service with systemd of centos 7.7 (systemd - 219-67.el7_7.1) - as mentioned here ( as pointed out by angshu in one of the threads)
I dint face this while installing bahmni in on centos 7.6 which comes with older version of systemd (It is the recommended OS verion in Bahmni wiki as well). I would suggest you to use the same if possible.
It might need some analysis and fixing in product to get openmrs working for newer versions of systemd.
If you really want to go ahead with 7.7 - you could try downgrading systemd by running -
yum downgrade systemd.x86_64 systemd-libs.x86_64 systemd-sysv.x86_64.
This will downgrade systemd to 219-67.el7. I tried it on my vagrant - it works.