Update vsa navigation specs for the horizontal flow

What does this MR do?

With the recent additional feature additions to custom value streams and removal of the legacy stage navigation we had some gaps in our testing.

This MR introduces some additional feature specs to cover some scenarios:

• Creating / Editing / Deleting value streams
• Re-ordering value stream stages
• Testing for a group and also for subgroups

Issue: #246493 (closed)

Additional some useful methods are moved to helpers

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
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Security

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