Dropped the dependency on TagInfo from LArG4GenShowerLib
This commit is a part of the effort to reduce the number of clients of TagInfo
in Athena to the bare minimum. After that the TagInfo
handling mechanism should
be redesigned, in order to make it MT-compliant.
LArG4GenShowerLib
used TagInfo
only for querying it for the release information.
The latter information can be obtained from the environment variables instead.