refactor: replace dynamic key generation with constant for SciCrunch instance retrieval

Author: pcrespov

services/web/server/src/simcore_service_webserver/scicrunch/service_client.py

@@ -60,15 +60,15 @@ def acquire_instance(
         cls, app: web.Application, settings: SciCrunchSettings
     ) -> "SciCrunch":
         """Returns single instance for the application and stores it"""
-        obj: SciCrunch | None = app.get(f"{__name__}.{cls.__name__}")
+        obj: SciCrunch | None = app.get(_SCICRUNCH_KEYAPP)
         if obj is None:
             session = get_client_session(app)
-            app[f"{__name__}.{cls.__name__}"] = obj = cls(session, settings)
+            app[_SCICRUNCH_KEYAPP] = obj = cls(session, settings)
         return obj
 
     @classmethod
     def get_instance(cls, app: web.Application) -> "SciCrunch":
-        obj: SciCrunch | None = app.get(f"{__name__}.{cls.__name__}")
+        obj: SciCrunch | None = app.get(_SCICRUNCH_KEYAPP)
         if obj is None:
             raise ScicrunchConfigError(
                 details="Services on scicrunch.org are currently disabled"
@@ -171,3 +171,6 @@ async def search_resource(self, name_as: str) -> list[ResourceHit]:
         # Might be good to know that scicrunch.org is not reachable and cannot perform search now?
         hits = await autocomplete_by_name(name_as, self.client, self.settings)
         return hits.root
+
+
+_SCICRUNCH_KEYAPP = web.AppKey(SciCrunch.__name__, SciCrunch)