Merge bitcoin/bitcoin#28035: test: Ignore UTF-8 errors in assert_debug_log

fa3d72960b lint: Ignore check_fileopens failure on **kwargs (MarcoFalke)
fa6bb85cd2 test: Ignore UTF-8 errors in assert_debug_log (MarcoFalke)
fa63326fbc test: Fix debug_log_size helper (MarcoFalke)

Pull request description:

  Fix two bugs, see commit messages.

ACKs for top commit:
  theStack:
    utACK fa3d72960b

Tree-SHA512: 4a29bdf954bf62bb7676c2a41b03ad017bc86d535b2bd912c96bd41d1621beb06d840b53c211480ad51974e8b293bbae620060d2528d269159f32c0b44e47712

test/functional/test_framework/test_node.py

@@ -424,8 +424,8 @@ class TestNode():
     def wallets_path(self) -> Path:
         return self.chain_path / "wallets"
 
-    def debug_log_bytes(self) -> int:
-        with open(self.debug_log_path, encoding='utf-8') as dl:
+    def debug_log_size(self, **kwargs) -> int:
+        with open(self.debug_log_path, **kwargs) as dl:
             dl.seek(0, 2)
             return dl.tell()
 
@@ -434,13 +434,13 @@ class TestNode():
         if unexpected_msgs is None:
             unexpected_msgs = []
         time_end = time.time() + timeout * self.timeout_factor
-        prev_size = self.debug_log_bytes()
+        prev_size = self.debug_log_size(encoding="utf-8")  # Must use same encoding that is used to read() below
 
         yield
 
         while True:
             found = True
-            with open(self.debug_log_path, encoding='utf-8') as dl:
+            with open(self.debug_log_path, encoding="utf-8", errors="replace") as dl:
                 dl.seek(prev_size)
                 log = dl.read()
             print_log = " - " + "\n - ".join(log.splitlines())
@@ -465,7 +465,7 @@ class TestNode():
             the number of log lines we encountered when matching
         """
         time_end = time.time() + timeout * self.timeout_factor
-        prev_size = self.debug_log_bytes()
+        prev_size = self.debug_log_size(mode="rb")  # Must use same mode that is used to read() below
 
         yield