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/helpers.py

@@ -14,7 +14,7 @@ from pydantic import BaseModel
 
 from lnbits import core
 from lnbits.db import DB_TYPE, POSTGRES, FromRowModel
-from lnbits.wallets import get_wallet_class, set_wallet_class
+from lnbits.wallets import get_funding_source, set_funding_source
 
 
 class DbTestModel(FromRowModel):
@@ -23,10 +23,10 @@ class DbTestModel(FromRowModel):
     value: Optional[str] = None
 
 
-def get_random_string(N: int = 10):
+def get_random_string(iterations: int = 10):
     return "".join(
         random.SystemRandom().choice(string.ascii_uppercase + string.digits)
-        for _ in range(N)
+        for _ in range(iterations)
     )
 
 
@@ -34,9 +34,9 @@ async def get_random_invoice_data():
     return {"out": False, "amount": 10, "memo": f"test_memo_{get_random_string(10)}"}
 
 
-set_wallet_class()
-WALLET = get_wallet_class()
-is_fake: bool = WALLET.__class__.__name__ == "FakeWallet"
+set_funding_source()
+funding_source = get_funding_source()
+is_fake: bool = funding_source.__class__.__name__ == "FakeWallet"
 is_regtest: bool = not is_fake