* charm-helpers sync for classic charms
* build.lock file for reactive charms
* ensure tox.ini is from release-tools
* ensure requirements.txt files are from release-tools
* On reactive charms:
- ensure stable/21.04 branch for charms.openstack
- ensure stable/21.04 branch for charm-helpers
Change-Id: I3b8e6ccdf10bf5a128f67b233e0218e16a8765ab