misc: simplify tor proxy URL to avoid circuit exhaustion

misc.py

@@ -187,12 +187,9 @@ def categorize_error(exc):
 
 
 def tor_proxy_url(torhost):
-    """Generate Tor SOCKS5 proxy URL with random credentials for circuit isolation.
+    """Generate Tor SOCKS5 proxy URL.
 
-    Tor treats different username:password as separate streams, using different
-    circuits. This ensures each connection gets a fresh circuit.
+    Uses no auth to allow Tor to reuse circuits naturally, avoiding
+    circuit exhaustion from IsolateSOCKSAuth behavior.
     """
-    chars = string.ascii_lowercase + string.digits
-    user = ''.join(random.choice(chars) for _ in range(8))
-    passwd = ''.join(random.choice(chars) for _ in range(8))
-    return 'socks5://%s:%s@%s' % (user, passwd, torhost)
+    return 'socks5://%s' % torhost