unittests/sht1x: decrease the amount of tested values on board
unittests/sht1x: decrease the amount of tested values on board

Reduce the amount of tested values by a 100.
This makes the testing time go from 3 minutes to 2 seconds on
`frdm-kw41z`.

Testing that the integer calculation matches the float one does not need
to be performed on the full range on boards. Checking some values should
be enough to detect overflow issues.
The full range checking is kept on native.

smlng/RIOT,kYc0o/RIOT,cladmi/RIOT,kaspar030/RIOT,basilfx/RIOT,kYc0o/RIOT,smlng/RIOT,rfuentess/RIOT,ant9000/RIOT,mtausig/RIOT,OTAkeys/RIOT,kaspar030/RIOT,jasonatran/RIOT,aeneby/RIOT,authmillenon/RIOT,miri64/RIOT,cladmi/RIOT,jasonatran/RIOT,x3ro/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,rfuentess/RIOT,aeneby/RIOT,kaspar030/RIOT,toonst/RIOT,cladmi/RIOT,miri64/RIOT,authmillenon/RIOT,x3ro/RIOT,miri64/RIOT,x3ro/RIOT,OlegHahm/RIOT,josephnoir/RIOT,kaspar030/RIOT,OlegHahm/RIOT,yogo1212/RIOT,cladmi/RIOT,jasonatran/RIOT,miri64/RIOT,toonst/RIOT,mtausig/RIOT,kaspar030/RIOT,kYc0o/RIOT,mtausig/RIOT,OTAkeys/RIOT,kYc0o/RIOT,mtausig/RIOT,toonst/RIOT,josephnoir/RIOT,basilfx/RIOT,josephnoir/RIOT,authmillenon/RIOT,smlng/RIOT,OlegHahm/RIOT,ant9000/RIOT,OTAkeys/RIOT,kYc0o/RIOT,OTAkeys/RIOT,rfuentess/RIOT,authmillenon/RIOT,ant9000/RIOT,toonst/RIOT,basilfx/RIOT,yogo1212/RIOT,yogo1212/RIOT,mtausig/RIOT,jasonatran/RIOT,jasonatran/RIOT,OTAkeys/RIOT,authmillenon/RIOT,yogo1212/RIOT,josephnoir/RIOT,authmillenon/RIOT,aeneby/RIOT,RIOT-OS/RIOT,basilfx/RIOT,ant9000/RIOT,OlegHahm/RIOT,rfuentess/RIOT,rfuentess/RIOT,ant9000/RIOT,miri64/RIOT,basilfx/RIOT,josephnoir/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,x3ro/RIOT,cladmi/RIOT,yogo1212/RIOT,yogo1212/RIOT,smlng/RIOT,aeneby/RIOT,smlng/RIOT,toonst/RIOT,x3ro/RIOT,aeneby/RIOT