Maintain PGDATA for postresql on OCP

[tarilabs]

Resolves #20

Description

Maintain PGDATA as required on OCP and other K8s clusters.

How Has This Been Tested?

BEFORE

Showing the issue:

initdb: error: directory "/var/lib/postgresql/data" exists but is not empty
initdb: detail: It contains a lost+found directory, perhaps due to it being a mount point.
initdb: hint: Using a mount point directly as the data directory is not recommended.
Create a subdirectory under the mount point.

AFTER

With this fix applied (kubectl apply -f config/samples/postgres-db.yaml):

Merge criteria:

• The commits and have meaningful messages; the author will squash them after approval or will ask to merge with squash.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work