Remove expired ports not depending on Python 2.7:

2020-12-31 devel/arm-none-eabi-gdb: This is an old, obsolete version of gdb
2020-12-31 devel/pecl-weakref2: PHP 7.2 extension
2020-12-31 graphics/py-imageio24: Use graphics/py-imageio instead
2020-12-31 mail/bogofilter-tc: TokyoCabinet is being phased out in favor of KyotoCabinet.
2020-12-31 net/pecl-yaz: PHP 7.2 extension
2020-12-31 print/cloudprint: Google Cloud Print is being shut down by Google by end of 2020
2020-12-31 science/py-eccodes-python: Use science/py-eccodes instead
2020-12-31 sysutils/cfengine-masterfiles312: EOL
2020-12-31 sysutils/cfengine-masterfiles313: EOL
2020-12-31 sysutils/cfengine312: EOL
2020-12-31 sysutils/cfengine313: EOL
2020-12-31 sysutils/rubygem-chef-zero5: Please use sysutils/rubygem-chef-zero instead
2020-12-31 sysutils/syslog-ng325: Reduction of syslog-ng ports to one
2020-12-31 sysutils/syslog-ng326: Reduction of syslog-ng ports to one
2020-12-31 sysutils/syslog-ng328: Reduction of syslog-ng ports to one
2020-12-31 sysutils/syslog-ng329: Reduction of syslog-ng ports to one
2020-12-31 www/flashplayer: Depends on a deprecated port
2020-12-31 www/linux-flashplayer: Deprecated by upstream
2020-12-31 www/mediawiki133: Upstream end of life
2020-12-31 www/mediawiki134: Upstream end of life
2020-12-31 www/py-aiohttp2: Use www/py-aiohttp instead

sysutils/drm-legacy-kmod is left in for now.