Remove Config Values as Env var in API server

[khrm]

Move these config values to the configmap so that changing configmap configures the value. Fixes #607

Changes

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Release Notes

DB_NAME and DB_HOST should be configurable via configmap.

[khrm]

/assign @enarha @avinal

[khrm]

/test pull-tekton-results-integration-tests

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: avinal

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[khrm]

/retest

[khrm]

@xinredhat Go coverage job was fixed.

[avinal]

/retest

[khrm]

@enarha Let's merge this.

[khrm]

@enarha Let's merge this for release also.

[khrm]

/kind misc