Add chain_id field to all block import test requests

- Add chain_id parameter to importBlock requests in all verification tests
- Update test_block_import.py to use high block heights to avoid conflicts with existing chain
- Simplify test_block_import.py to focus on core validation (hash, parent, conflict)
- Fix test_block_import_complete.py to use head block instead of block 1 for existing block test
- Update expected response format from status field to success field

tests/verification/test_simple_import.py

@@ -46,7 +46,8 @@ def test_simple_block_import():
             "parent_hash": parent_hash,
             "proposer": "test-proposer",
             "timestamp": timestamp,
-            "tx_count": 0
+            "tx_count": 0,
+            "chain_id": CHAIN_ID
         }
     )