[App] Hot Fix: Missing root flow in app.flows

[tchaton]

What does this PR do?

This change introduce the bug: 921dc1c#diff-6cbbb993a8c2bf30a487086dcd4cf9a595ffc7399ecfc3efbb79f7568a3b74c8L287.

The root flow should be listed among the flows.

Fixes #<issue_number>

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