Update to airflow-2.7.3 and install statsd support

This commit upgrades the airflow conda environmemt to version 2.7.3 which addresses a number of CVEs and offers some new features.

In addition to this we also install the statsd python module from pypi in order to support airflow metrics generation.

Finally, we install graphvix from pip instead of conda-forge in order to ensure cross-platform compatability of the conda-analytics.lock.yaml file.

Bug: T351621 Bug: T344602 Bug: T343232