AT4-1493: Adding a flag to argument while calling filtools

Software called filtools is used to inject pulses into the filterbank files containing noise. Now, the script used to generate the noise (fast_fake) produces has information of the sign of the data contained inside the filterbank, which does not work with ska-pss-cheetah. This problem can be mitigated by removing parameter from the header of the filterbank file. We have added this functionality to filtools which requires an argument to do so and the same has to be propogated to this repo as well.