See merge request nexedi/slapos!1322

See merge request nexedi/slapos!1365

Shorten the socket path
Add a promise to check socket

This updates python extension to a version supporting only python3.

To have full python2 support, it's possible to download
https://open-vsx.org/extension/ms-python/python/2020.10.332292344
and use "Install from VSIX" option and manually apply the patch to fix
perfomance issue with buildout paths:

    curl https://lab.nexedi.com/nexedi/slapos/raw/bdb7777beb34d8840cbbc498adba7a55d521079b/component/theia/ms-python-disable-jedi-buildout.patch | patch  ~/tmp/vscode-unpacked/ms-python.python-2020.10.332292344.vsix/extension/pythonFiles/lib/python/jedi/inference/sys_path.py

Set this as default version, there was no default version before.

This also introduce a step to download the tarball headers for node-gyp,
otherwise it will download it directly bypassing libnetworkcache.

- MariaDB 10.3.38 & 10.4.28
- mroonga 13.00
- groonga 13.0.0
- groonga-normalizer-mysql 1.2.1

We stopped using it because of 2 data integrity issues:
- https://jira.percona.com/browse/PS-5569 ("FT index corrupt")
- https://jira.percona.com/browse/PS-4291 ("DELETE sometimes do nothing")

TokuDB is also already disabled because transparent huge pages are
enabled by default.

There are more log files with neo

To run the benchmark locally:

 - Install software/slapos-sr-testing and create an instance
 - Source the shell script published by the instance to setup
   environment variables
 - execute `python_for_test -m unittest -v  test.benchmarks`

This promise was generally used to check the connection quality to the
backend with ICMP, by using ping. This is currently obsoleted by health-check
and other parameters in that group.

The parameter to setup the promise is provided by shared instance requester,
that person has no access to those results, as shared instances can't be
monitored directly, all results are only available to the cluster operator in
contrast to health-check, which results are logged to backend_log, to which
shared instance requester has access.

See merge request !1353

See merge request !1348