Description of problem:
When a migration plan is created with a long name, the registry pod cannot be created.


Version-Release number of selected component (if applicable):
CAM 1.1.2 stage
Target cluster: 4.3
Source cluster: 3.7

How reproducible:
Always

Steps to Reproduce:
1. Create a migration plan with more than 46 characters, for instance "ocp-29073-internalimagestream-migplan-1585911125"
2. Check the pods in openshift-migration namespace, there you should be a registry pod created for this migplan
oc get pods -n openshift-migration


Actual results:
The registry pod is not created, and an error is displayed in the namespace's events

$ oc get events -n openshift-migration | grep nalimage
5m14s       Warning   DeploymentCreationFailed   deploymentconfig/registry-ocp-29073-internalimagestream-migplan-1585911125-gfzcx   Couldn't deploy version 1: ReplicationController "registry-ocp-29073-internalimagestream-migplan-1585911125-gfzcx-1" is invalid: [spec.selector: Required value, spec.template.labels: Invalid value: "registry-ocp-29073-internalimagestream-migplan-1585911125-gfzcx-1": must be no more than 63 characters]

Expected results:
Migration plans with names that break the migration should not be allowed or, if they are allowed, a critical condition should be displayed.

Additional info:
Because of the registry pod not being created, we have this kind of errors when we execute migrations with internal images:

time="2020-04-03T11:24:52Z" level=info msg="[is-backup] Error copying image: Error trying to reuse blob sha256:aad63a9339440e7c3e1fff2b988991b9bfb81280042fa7
f39a5e327023056819 at destination: error pinging docker registry 172.30.153.130:5000: Get http://172.30.153.130:5000/v2/: dial tcp 172.30.153.130:5000: conne
ct: no route to host" backup=openshift-migration/aea7cfd0-759d-11ea-905a-0f252c857867-2rl4s cmd=/plugins/velero-plugins logSource="/go/src/github.com/fusor/o
penshift-migration-plugin/velero-plugins/migimagestream/backup.go:87" pluginName=velero-plugins
time="2020-04-03T11:24:52Z" level=info msg="1 errors encountered backup up item" backup=openshift-migration/aea7cfd0-759d-11ea-905a-0f252c857867-2rl4s group=
image.openshift.io/v1 logSource="pkg/backup/resource_backupper.go:284" name=internal-image namespace=ocp-29073-internalimagestream resource=imagestreams
time="2020-04-03T11:24:52Z" level=error msg="Error backing up item" backup=openshift-migration/aea7cfd0-759d-11ea-905a-0f252c857867-2rl4s error="error execut
ing custom action (groupResource=imagestreams.image.openshift.io, namespace=ocp-29073-internalimagestream, name=internal-image): rpc error: code = Unknown de
sc = Error trying to reuse blob sha256:aad63a9339440e7c3e1fff2b988991b9bfb81280042fa7f39a5e327023056819 at destination: error pinging docker registry 172.30.
153.130:5000: Get http://172.30.153.130:5000/v2/: dial tcp 172.30.153.130:5000: connect: no route to host" error.file="/go/src/github.com/vmware-tanzu/velero
/pkg/backup/item_backupper.go:334" error.function="github.com/vmware-tanzu/velero/pkg/backup.(*defaultItemBackupper).executeActions" group=image.openshift.io
/v1 logSource="pkg/backup/resource_backupper.go:288" name=internal-image namespace=ocp-29073-internalimagestream resource=imagestreams
time="2020-04-03T11:24:52Z" level=info msg="Backing up group" backup=openshift-migration/aea7cfd0-759d-11ea-905a-0f252c857867-2rl4s group=network.openshift.i
o/v1 logSource="pkg/backup/group_backupper.go:101"