Add conda container driven tests

This MR adds parallel set of tests in build suite that run in a conda container (as opposed to el7)

Motivation

Presently, the developer environment uses conda-flow to create locked python env files. This workflow has superior reproducibility to the yum-based python environment install in the el7 containers that drive the test suite and production usage. In an effort to minimize diffs between dev and prod envs, this mr adds a full conda container that could be run in production. Caveat: MKL integration is going to be a separate MR.

Changes

• update conda docker image to use env lock files
• update conda docker image to include gds plugins
• update conda docker image to include gstlal-calibration subpackage
• add test jobs to build suite that use conda container instead of el7