Make failure to increase the recv buffer size non-fatal

We now try to set the buffer to
2097152, 1048576, 524288, 262144, 131072

before giving up and logging a warning

tests/test_connection.py

@@ -281,6 +281,9 @@ def _setsockopt(*args, **kwargs):
     assert "Unable to increase the socket receive buffer size to 131072" in caplog.text
     assert tried_sizes == [2097152, 1048576, 524288, 262144, 131072]
 
+    # Failure to increase the buffer size should not cause the connection to fail
+    assert conn.is_connected
+
 
 @pytest.mark.asyncio
 async def test_start_connection_can_only_increase_buffer_size_to_262144(
@@ -327,6 +330,9 @@ def _setsockopt(*args, **kwargs):
     assert "Unable to increase the socket receive buffer size" not in caplog.text
     assert tried_sizes == [2097152, 1048576, 524288, 262144]
 
+    # Failure to increase the buffer size should not cause the connection to fail
+    assert conn.is_connected
+
 
 @pytest.mark.asyncio
 async def test_start_connection_times_out(