chore: adhere to ruff's "N" rules (#2377)

* chore: adhere to ruff's "N" rules

WARN: reinstall failing extensions!

bunch of more consistent variable naming. inspired by this issue.
https://github.com/lnbits/lnbits/issues/2308

* fixup! chore: adhere to ruff's "N" rules
* rename to funding_source
* skip jmeter

---------

Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

tests/core/views/test_node_api.py

@@ -10,14 +10,15 @@ from lnbits.nodes.base import ChannelPoint, ChannelState, NodeChannel
 from tests.conftest import pytest_asyncio, settings
 
 from ...helpers import (
-    WALLET,
+    funding_source,
     get_random_invoice_data,
     get_unconnected_node_uri,
     mine_blocks,
 )
 
 pytestmark = pytest.mark.skipif(
-    WALLET.__node_cls__ is None, reason="Cant test if node implementation isnt avilable"
+    funding_source.__node_cls__ is None,
+    reason="Cant test if node implementation isnt available",
 )