databases/pgpool-II-41: Update version 4.1.2=>4.1.6

• Pet portlint
• Fix pkg-plist. Except the default pgpool.conf.sample other pgpool.conf.sample* represents different configurations for different scenario. Only the pgpool.conf.sample should create a corresponding pgpool.conf file. Hence removing the @sample directive for the other pgpool.conf.sample*

Approved by: tz
Relnotes: https://www.pgpool.net/docs/latest/en/html/release-4-1-6.html
Sponsored by: Bounce Experts
Differential Revision: https://reviews.freebsd.org/D30177