fix(telegram): improve MarkdownV2 edit fallback and fix _strip_mdv2 bold handling

When edit_message(finalize=True) fails with a MarkdownV2 parse error,
the silent fallback previously sent raw content with escape sequences.
Now it logs the error and strips markdown formatting via _strip_mdv2()
for clean plain-text fallback.

Also fixes _strip_mdv2 to handle standard markdown bold (\*\*text\*\*)
before MarkdownV2 bold (\*text\*), preventing half-stripped asterisks.

Refs: #41955, #41732

tests/gateway/test_telegram_format.py

@@ -835,7 +835,7 @@ class TestEditMessageStreamingSafety:
         assert second_call == {
             "chat_id": 123,
             "message_id": 456,
-            "text": "final **bold**",
+            "text": "final bold",
         }
 
     @pytest.mark.asyncio