chore: improve integration tests (#8727)

Improve integration tests:
- spliting the tests in TokenExchange to isolated instances and in
parallel
- corrected some test structure so that the check for Details is no done
anymore if the test already failed
- replace required-calls with assert-calls to not stop the testing
- add gofakeit for application, project and usernames(emails)
- add eventually checks for testing in actions v2, so the request only
get called when the execution is defined
- check for length of results in list/search endpoints to avoid index
errors

internal/notification/handlers/integration_test/telemetry_pusher_test.go

@@ -25,6 +25,8 @@ import (
 )
 
 func TestServer_TelemetryPushMilestones(t *testing.T) {
+	t.Parallel()
+
 	sub := sink.Subscribe(CTX, sink.ChannelMilestone)
 	defer sub.Close()