remove component mcc/mcd/mco/mcs/setupetcdenv rhel7 dockerfiles

[kikisdeliveryservice]

Since all component images have been folded into 1 master mco image,
remove rhel7 dockerfiles pending merge of ocp-build-data/merge_requests/181

Related-to: #739
Followup-to: #895

close #739
close #421

[kikisdeliveryservice]

/hold

[runcom]

internal PR has been merged and we have a go ahead to merge this

/approve
/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kikisdeliveryservice, runcom

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[runcom]

/hold cancel

[runcom]

Installing from release registry.svc.ci.openshift.org/ci-op-b434wzxt/release@sha256:cb1ffd1de810aa4b5ea0e6b2648f4a635e560015aa28e9b6806a61c52c39b38b
level=fatal msg="failed to fetch Terraform Variables: failed to fetch dependency of \"Terraform Variables\": failed to fetch dependency of \"Bootstrap Ignition Config\": failed to fetch dependency of \"Common Manifests\": failed to generate asset \"DNS Config\": getting public zone for \"origin-ci-int-aws.dev.rhcloud.com\": listing hosted zones: Throttling: Rate exceeded\n\tstatus code: 400, request id: f2eb330c-68f8-4038-a779-76862d0c2d2a"

/retest