Move to Deployment from DeploymentConfig for investigator and metrics-exporter

[harshad16]

Is your feature request related to a problem? Please describe.
We follow openshift principles for deployments and have been using deployment config since OCP 3.11, with OCP 4.6 it is observed that openshift recommends using either one based on requirements.
As we have limited resource quota in namespace thoth-infra-stage
where workloads like investigator and metrics-exporter are executed.
with the growth of these applications, it would help with the deployment process
if we update them to the Deployment method instead of DeploymentConfig.
As it would remove the necessity to track the resource utilization by the deploy pod of DeploymentConfig.

https://github.com/thoth-station/thoth-application/blob/master/investigator/base/deploymentconfig.yaml
https://github.com/thoth-station/thoth-application/blob/master/metrics-exporter/base/deploymentconfig.yaml

Describe the solution you'd like
Simple update of investigator and metrics-exporter to deployment

Describe alternatives you've considered
Increasing the resource quota, (which has it whole tendious process of ticketing)
only to be done when required.

[harshad16]

/triage accepted
/sig devsecops
/priority important-soon