init_rucio.sh for rucio client container needs update for v39.0.0

[tsgit]

Hi,

the rucio client container has

https://github.com/rucio/containers/blob/master/clients/init_rucio.sh#L10

which no longer matches the location of the script in rucio 39.0.0 release which is

/usr/local/rucio/tools/merge_rucio_configs.py

so the client comes up with no config.

Thanks
T.