Remove expired ports:

2021-03-31 www/gtkhtml3: Obsolete by upstream, doesn't build with recent versions of pango
2021-03-31 deskutils/tomboy: Unmaintained and dead upstream, depends on deprecated libraries  such as www/gtkhtml3. Upstream project is now called tomboy-ng.
deskutils/tomboy-plugin-reminder: part of deskutils/tomboy
2021-03-31 devel/monodevelop: outdated, depends on deprecated library www/gtkhtml3
2021-03-31 sysutils/syslog-ng327: Not officially supported by upstream
2021-03-31 sysutils/logstash5: End of life since release of 7.3.0
2021-03-31 www/decss: Abandonware
2021-03-31 textproc/elasticsearch5: End of life since release of 7.3.0
2021-03-31 textproc/elasticsearch5-search-guard: textproc/elasticsearch5 is scheduled for removal
2021-03-31 multimedia/gnome-subtitles: outdated, depends on deprecated library www/gtkhtml3
2021-03-31 net/libproxy-mozjs: Uses EOL Python 2.7 via lang/spidermonkey52
2020-12-31 lang/spidermonkey52: Uses Python 2.7 which is EOLed upstream