LALSimInspiral.c: Don't modify f_min for NR_hdf5

This patch modifies the LALSimulation function XLALSimInspiralTDFromTD, which is called by XLALSimInspiralTD, to make it more useable when using Numerical Relativity waveforms.

XLALSimInspiralTD can be used to generate conditioned waveforms from both approximants in the Time- and Frequency-domain. You call XLALSimInspiralTD with a start frequency f_min and inside XLALSimInspiralTDFromTD f_min gets modified to become a slightly lower frequency. This is because some conditioning is applied at the start of the waveform.

The problem when using NR waveforms is that they have a finite length. So requesting the waveform at a slightly lower frequency will not work for NR waveforms when you want to use the complete waveform.

This MR implements a simple switch that avoids changing the start frequency when calling attempting to generate an NR waveform.

This fix was necessary for the current method of injecting NR waveforms in the CWB pipeline. I also suspect that it will be necessary for the GSTLAL pipeline as I think it uses XLALSimInspiralTD.

People of interest: @ian-harry, @francesco.salemi, @jolien-creighton