[minor][bugfix] Remove redundant generateName

[cloudw]

When creating a workflow with a specific name using python <flow.py> create --name <name>, the compiled workflow template manifest contains both generateName and name under metadata field.

For example, the output template of a recent pipeline https://gitlab.zgtools.net/analytics/artificial-intelligence/ai-platform/aip-infrastructure/integration-tests/aip-workflow-example/-/jobs/42159367 has manifest that looks like the following:

apiVersion: argoproj.io/v1alpha1
kind: WorkflowTemplate
metadata:
  generateName: exampleflow-
  name: example-flow-95623b8e
  annotations: {}
  labels: {
    metaflow.org/flow_name: ExampleFlow,
    metaflow.org/tag_project-name: aip-workflow-example,
    metaflow.org/tag_pipeline-id: '6821369',
    metaflow.org/tag_commit-sha: 95623b8eb6146e5c33e526dfbcbc946828565541,
    zodiac.zillowgroup.net/owner: None,
    zodiac.zillowgroup.net/product: batch
  }
... (more fields below)

where the name: example-flow-95623b8e is expected (as flow name + commit sha) but the generateName: exampleflow- is redundant.

Further looking into the code, it looks like when a specific --name is provided, the current logic prevent generateName from being popped out.

[cavandervoort]

It looks good to me. The logic results in the same name being generated, but taking the .pop() of generateName outside of the if/else section ensures that .pop() is run.