Fix the path when running with HYDRA_BACKEND set (#2216)

The path was definitely wrong; but I think the tests still fail.

-- edit: You can see the tests still fail:
https://github.com/cardano-scaling/hydra/actions/runs/17374716893/job/49318370147

Author: noonio

hydra-cluster/src/CardanoNode.hs

@@ -169,7 +169,7 @@ withBlockfrostBackend ::
 withBlockfrostBackend _tracer stateDirectory action = do
   args <- setupCardanoDevnet stateDirectory
   shelleyGenesis <- readFileBS >=> unsafeDecodeJson $ stateDirectory </> nodeShelleyGenesisFile args
-  let backend = BlockfrostBackend $ BlockfrostOptions{projectPath = ".." </> Backend.blockfrostProjectPath}
+  let backend = BlockfrostBackend $ BlockfrostOptions{projectPath = Backend.blockfrostProjectPath}
   action (getShelleyGenesisBlockTime shelleyGenesis) backend
 
 withBackend ::