grpc2py: fix F401 and E261 flake8 violations in generator and generated output

The generator emitted `import json` in its header template despite json
never being referenced in the generated output (F401), and used a single
space before three inline `#` comments (E261). Fix by removing the unused
import from the template and adding the required second space before each
comment. Regenerate the output file accordingly.

Changelog-None

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

contrib/msggen/msggen/gen/grpc2py.py

@@ -83,9 +83,6 @@ def generate(self, service: Service) -> None:
         # `doc/schemas`. Do not edit this file manually as it would get
         # overwritten.
 
-        import json
-
-
         def hexlify(b):
             return b if b is None else b.hex()
 
@@ -109,7 +106,7 @@ def remove_default(d):
         self.write("""\
 
 
-        def decodekeysend_routes2py(m): # manual override
+        def decodekeysend_routes2py(m):  # manual override
             return remove_default({
                 "expirydelta": m.expirydelta,
                 "feebase": amount2msat(m.feebase),
@@ -122,7 +119,7 @@ def decodekeysend_routes2py(m): # manual override
         self.write("""\
 
 
-        def decodepay_routes2py(m): # manual override
+        def decodepay_routes2py(m):  # manual override
             return remove_default({
                 "cltv_expiry_delta": m.cltv_expiry_delta,
                 "fee_base_msat": amount2msat(m.fee_base_msat),
@@ -189,7 +186,7 @@ def {converter_name}(m):
             elif isinstance(f, ArrayField) and isinstance(f.itemtype, PrimitiveField):
                 rhs = self.converters[f.itemtype.typename].format(name=name)
                 self.write(
-                    f'        "{name}": [{rhs} for i in {rhs}], # ArrayField[primitive] in generate_composite\n',
+                    f'        "{name}": [{rhs} for i in {rhs}],  # ArrayField[primitive] in generate_composite\n',
                     cleanup=False,
                 )