BAH-1527 | Fix Postgres installation from local artifacts.

[mohan-13]

• Removes the installation of pgdg-redhat repo RPM.
• Installs postgres server and required dependencies from local artifacts.

With this new installer, the below commands needs to be triggered.

cd /opt
wget https://repo.mybahmni.org/releases/postgresql96-9.6.24-1PGDG.rhel7.x86_64.rpm
wget https://repo.mybahmni.org/releases/postgresql96-server-9.6.24-1PGDG.rhel7.x86_64.rpm
wget https://repo.mybahmni.org/releases/postgresql96-libs-9.6.24-1PGDG.rhel7.x86_64.rpm
wget https://repo.mybahmni.org/releases/postgresql96-contrib-9.6.24-1PGDG.rhel7.x86_64.rpm

After this the installer can be fired as usual
bahmni -i local install

[mohan-13]

The artifacts in our S3 repo are not found by yum during installation because the metadata was not updated after the artifacts are uploaded. Now that has been resolved in our S3 releases repository. So the manual steps to download the artifacts are not needed.

[mohan-13]

Since we are using our S3 releases repository, installing of pgdg-redhat-repo rpm is not needed. Will remove that in this PR