ATR-28398: Fix for Run-2 RDOtoRDOTrigger running on the grid

!67316 (merged) has missed in one place the working directory structure for transforms running on the grid.
The workdir is /srv/workDir, where my_setupATLAS.sh is created.
Before calling this script, the directory is changed to /srv (needed for launching a nested container) and of course "./my_setupATLAS.sh" doesn't work from there. This MR changes to the absolute path of my_setupATLAS.sh for launching the container.
Tested with a grid-like parent container setup (missed this during testing last time):

setupATLAS -c el9 -e "-C"
asetup Athena,main,latest
mkdir workDir && cd workDir
ATHENA_CORE_NUMBER=0 Reco_tf.py  --AMIConfig q443 --imf False --CA all:True RDOtoRDOTrigger:False --conditionsTag default:OFLCOND-MC16-SDR-RUN2-11 RDOtoRDOTrigger:OFLCOND-MC16-SDR-RUN2-08-02 --maxEvents 1