Remove ignore_timestamps_error in OpenEphysRawIO

[alejoe91]

Describe the bug
In #1213 we added the option to ignore timestamps errors in the Open Ephys legacy format. However, it turns out that these discontinuities could be uneven across files, so it's not a good idea to jus ignore them.

Expected behaviour
A better solution would be to "fill in" the missing timestamps with zeros (or NaNs) at the get_signal_analog_chunk level, so that all data is at least aligned

[zm711]

Fixed by #1387.