Re-enable repository tests (#2451)

## Description

The load tests (`repository_load_test.go`) overrides the default [TestMain](https://medium.com/goingogo/why-use-testmain-for-testing-in-go-dafb52b406bc).

This results in the other tests in the repository_test package not running.

The fix is to move the load tests into a sub-package

## Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No 

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [x] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

## Test Plan

<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [ ] ⚡ Unit test
- [x] 💚 E2E

src/Makefile

@@ -74,4 +74,4 @@ load-test:
 	-mutexprofile=mutex.prof \
 	-trace=trace.out \
 	-outputdir=test_results \
-	./pkg/repository/repository_load_test.go
+	./pkg/repository/loadtest/repository_load_test.go