chore(orchestration): prevent throwing on already defined workflow (#5337)

**What**
At the moment, when importing something from medusa entry point, if two medusa packages are installed because of a plugin, the evaluation of the import can end up throwing that a workflow is already defined. To prevent that from happening, we can just not throw if it is already defined and just return prematurely and make it idempotent.

.changeset/strong-dragons-flow.md

@@ -0,0 +1,6 @@
+---
+"@medusajs/orchestration": patch
+"@medusajs/utilsgst": patch
+---
+
+chore(orchestration): prevent throwing on already defined workflow