Remove extra code for SubxtClient for integration tests

[ebma]

We should be able to remove the extra code for the client we have for the vault's integration tests. It's favorable to remove this code if we can to simplify the setup of the integration tests.

For reference, have a look at this setup of the integration tests.

[ebma]

@pendulum-chain/product this ticket is just about some refactorings. It is merely nice to have and not required for anything. Thus, it's of rather low priority.

[annatekl]

Hey team! Please add your planning poker estimate with Zenhub @adelarja @b-yap @ebma @gianfra-t @TorstenStueber

[prayagd]

@b-yap are you working on this? should i move this to ready or development?

[ebma]

@b-yap asked to be assigned to some of the low-prio refactoring tickets because she is most suited to work on them. But they are not in development yet. Just treat them as if they were not assigned to anyone.

[prayagd]

Thanks Marcel, will move it to bottom in ready column

[prayagd]

@b-yap what's the status here? hasnt been updated since nov '23 should we close or icebox it?

[b-yap]

@prayagd working on this again.
@prayagd yes please, we should icebox this. There's more issues to do, and this is not as urgent.