Revert "BLXI-225: provide unit for the 'count_time' data in the detector nexus data file http://jira.diamond.ac.uk/browse/BLXI-225"

This reverts commit 01347afea4776b6a69d659bbdefac5aa3b6317ba.
BLXI-225: provide unit for the 'count_time' data in the detector nexus data file
http://jira.diamond.ac.uk/browse/BLXI-225
make sure both wavelength and energy from monochromator be written in file if both provided.
Merge branch 'gda-8.42' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git into gda-8.42