chore: simplify lifespan setup

Author: alukach

src/stac_auth_proxy/app.py

@@ -31,16 +31,13 @@ def create_app(settings: Optional[Settings] = None) -> FastAPI:
     #
     # Application
     #
-    upstream_urls = [
-        settings.upstream_url,
-        settings.oidc_discovery_internal_url or settings.oidc_discovery_url,
-    ]
+    upstream_urls = (
+        [settings.upstream_url, settings.oidc_discovery_internal_url]
+        if settings.wait_for_upstream
+        else []
+    )
     lifespan = LifespanManager(
-        on_startup=(
-            [ServerHealthCheck(url=url) for url in upstream_urls]
-            if settings.wait_for_upstream
-            else []
-        )
+        on_startup=([ServerHealthCheck(url=url) for url in upstream_urls])
     )
 
     app = FastAPI(