Update db test secrets to allow passing of prodsec scanning.

[tonyxrmdavidson]

This commit will allow the test credentials for the postgress and mysql databases to pass prodsec scanning.

It should stop emails being received by the team informing us we have a potential data leak because of test credentials.

Instructions on how should be done are found here.

Description

Added '# notsecret tag to database-password and database-user lines in both postgres-db.yaml and mysql-db.yaml

Added a .gitleaks.toml file to allow prodsec to scan all previous commits.

How Has This Been Tested?

It has been tested locally using gitleaks cli.

[openshift-ci]

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This pull-request has been approved by: tonyxrmdavidson

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[tarilabs]

/lgtm

thanks Tony

per my previous #76 (review)
if the samples manifests are taken from the ODH/MRO repo programmatically, one reason more to just need to maintain the .gitleaks.toml is the only source-of-truth place, my2c