<run|cleanup> packagemanifests: remove --olm-namespace, change --operator-namespace to --namespace

[estroz]

Description of the change:

• internal/olm/operator: remove OLM namespace usage, OLM installation detection, create resources in provided operator namespace, and change operator namespace to namespace
• website: update docs

Motivation for the change: <run|cleanup packagemanifests flag --olm-namespace has been removed since it is no longer used by the command, and --operator-namespace has been renamed to --namespace. OLM-adjacent resources (ex. registry deployment) are now created in the provided namespace, and OLM installation is no longer checked.

/cc @joelanford @jmrodri @rashmigottipati

Checklist

If the pull request includes user-facing changes, extra documentation is required:

• Add a new changelog fragment in changelog/fragments (see changelog/fragments/00-template.yaml)
• Add or update relevant sections of the docs website in website/content/en/docs

[rashmigottipati]

/lgtm

after fixing typo in log message and CI passes

[jmrodri]

/lgtm

[jmrodri]

+1 to using the past tense, Removed, it reads better when the changelog is generated.

[jmrodri]

+1 to Changed

[joelanford]

/lgtm

[jmrodri]

@estroz test broke

Unexpected error:

        <*errors.errorString | 0xc00003e480>: {

            s: "operator-sdk run packagemanifests --install-mode AllNamespaces --operator-namespace e2e-dvvb-system --version 0.0.1 --timeout 4m failed with error: Error: unknown flag: --operator-namespace\nUsage:\n  operator-sdk run packagemanifests [flags]\n\nAliases:\n  packagemanifests, pm\n\nFlags:\n  -h, --help                  help for packagemanifests\n      --install-mode string   InstallMode to create OperatorGroup with. Format: InstallModeType[=ns1,ns2[, ...]]\n      --kubeconfig string     The file path to kubernetes configuration file. Defaults to location specified by $KUBECONFIG, or to default file rules if not set\n      --namespace string      The namespace where operator resources are created. It must already exist in the cluster\n      --timeout duration      Time to wait for the command to complete before failing (default 2m0s)\n      --version string        Packaged version of the operator to deploy\n\nGlobal Flags:\n      --verbose   Enable verbose logging\n\ntime=\"2020-07-29T20:37:23Z\" level=fatal msg=\"unknown flag: --operator-namespace\"\n",```

[rashmigottipati]

One clarification: we probably need to change this from --operator-namespace to --namespace in e2e tests too, right?

[openshift-ci-robot]

New changes are detected. LGTM label has been removed.