fix: Medusa service base method transaction (#7758)

**What**
Remove transaction decorator from the base medusa service method, the transaction will always be coming from the shared context. It fixes the issue that when you consume a base method directly it will return a proper tuple from the DB instead of the one from the entity map cc @VariableVic 

**NOTE**
This pr also fix some categories issues in the product module which was preventing the tests from working. if @sradevski you could have a look later, in the mean time we can still merge it

FIXES CORE-2342

packages/modules/workflow-engine-inmemory/integration-tests/__tests__/index.spec.ts

@@ -31,7 +31,7 @@ const afterEach_ = async () => {
   await TestDatabase.clearTables(sharedPgConnection)
 }
 
-jest.setTimeout(50000)
+jest.setTimeout(100000)
 
 describe("Workflow Orchestrator module", function () {
   let workflowOrcModule: IWorkflowEngineService