databases/timescaledb: Update to 1.2.0

This release adds Timescale Licensed code that can be turned off with a new
build time option, APACHEONLY, to retain Apache licensing.

Changelog https://github.com/timescale/timescaledb/releases/tag/1.2.0

Approved by: timur (mentor)
Sponsored by: BBOX.io
Differential Revision: https://reviews.freebsd.org/D19035