MGMT-15367: Custom manifests names should be unique

[ammont82]

Related to https://issues.redhat.com/browse/MGMT-15367

Custom manifest files should be unique as openshift folder files are merged to manifests.

Before changes you can have same file name in different folders for custom manifests:

After changes you custom manifests file names should be unique regardless folder:

[openshift-ci-robot]

@ammont82: This pull request references MGMT-15367 which is a valid jira issue.

In response to [this](https://github.com/openshift-assisted/assisted-installer-ui/pull/2277): >Related to https://issues.redhat.com/browse/MGMT-15367 > >Custom manifest files should be unique as openshift folder files are merged to manifests. > >Before changes you can have same file name in different folders for custom manifests: > > >After changes you custom manifests file names should be unique regardless folder: > > Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[jgyselov]

There will be conflicts between this and #2278. I suggest we merge this one first.

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: ammont82, jgyselov, jkilzi

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