#5092 Fix RingBuffer's c_get_as_numpy_array() doesn't return the correct array

After adding a sample to the RingBuffer, start and stop indexes are updated. When calling the c_get_as_numpy_array() afterwards, the method doesn't account for the shifted indexes (in case the buffer is already filled).

As a result it returns an array with wrong data.

Link: https://github.com/hummingbot/hummingbot/pull/5092