Update gate jobs as per the 2023.1 cycle testing runtime

As per 2023.1 testing runtime[1], we need to test on Ubuntu
Jammy (which will be taken care by tempest and devstack patches
to move base jobs to Jammy) and at least single job to run on
Ubutnu Focal (for smooth upgrade). Also, python 3.10 testing is
voting now.

This commit adds a new job to run on focal which can be removed
in future cycle when testing runtime drop the requirement of Focal
testing. Also, make python 3.10 functional and unit test job as voting
(openstack-tox-py310 is running as part of generic template so we do
not need to explicitly add that)

[1] https://governance.openstack.org/tc/reference/runtimes/2023.1.html

Change-Id: Ia43f73dba00b0b5932939bcc7d11b97a83072ee3

setup.cfg

@@ -22,6 +22,7 @@ classifiers =
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: Implementation :: CPython