Injector: ignore operations which already exist when adding

Context

In some cases (especially in tezt tests settings where timestamps are not real), it can happen that the rollup node adds operations twice to the injector if the previous one was already injected. The injector used to ignore only operations that were already in the queue. This MR makes the injector also check for existence in the injected and included operations.

Because there is a user configurable retention period for included operations, we make the injector check for operations that are not confirmed yet.

Needed for tests of !7792 (merged).

Manually testing the MR

CI.