allow narrow down e2e testing scope

[Ivansete-status]

This is a proposal to reduce the scope when performing e2e tests in both Desktop and Mobile.
The idea is to allow running the e2e tests against one single datacenter, f.e, status.staging-AMS (1 boot, 2 store, 1 db.)

With that, we will have two benefits:

1. It is easier to debug issues as we will know which are the impacted nodes
2. Minimize the impact on e2e tests while the Waku team is debugging a particular issue in a different datacenter, f.e., status.staging-HK.

( cc @anastasiyaig )

[anastasiyaig]

from desktop client we need (ideally):

• build with staging fleet already selected (could be treated as "special build for autotests")
• teach the app how to select a certain datacenter on the fleet so i can replicate it in tests
• ideally, use linux nix build for that (but thats not mandatory, i just want newer qt )

right now changing fleet is pain for tests becuause i first need to start the app with a special flag and then change fleet and then restart. would be much easier to have it already predefined so i dont need to hack tests doing it

@igor-sirotin @richard-ramos

[anastasiyaig]

@churik ^^

[churik]

From mobile side:

• we need a param to set a specific store node (in config would be the best)
• turn off automatic selection of store nodes or make it configurable
• make Display in app settings to which mailserver profile is currently connected status-mobile#21375 and also log the store node where the app is currently connected

cc @ilmotta