Fix for #20200514-218C705 - \[testnode\] frontend for log access

Depends on nexedi/erp5!1304

See merge request nexedi/slapos!848

This fixes the nextcloud SR, which was broken by
commit 92779bf4
(mariadb is not a part anymore).

This fixes commit a62e5e7b.
See also commit 491e6e28.

And set it as log_frontend_url in testnode config

Just add the following 2 lines in a SR:

[mariadb]
location = ${mariadb-10.4:location}

It does not build with GCC 8.2

Going Go1.14.9 -> Go1.14.10 brings in compiler and runtime fixes
including fix for crash in garbage-collector due to race condition:

https://github.com/golang/go/issues/40642
https://github.com/golang/go/issues/40641

Tested on helloworld SR.

See merge request nexedi/slapos!844

validators.url is enough, even for Caddy, to check that URL is correct, and
caddy_backend_url_validator was introduced before validators.

Also calling an external command for each slave takes a lot of time.

Thanks to this other sections can directly reference them, and so they are
correctly created as needed, so linking section does not need update-command

The password is anyway present in the section itself, so it's eventual change
will result with reinstalling the section.

Also change a bit existing frontend_url to manage it the same way.

This way buildout can reuse egg caches and it's a bit faster:

To run a simple instance buildout, from 2.837s it goes down to 1.875s.
To run slapos node instance 10 times just after requesting an ERP5 instance, it goes from ~112s to 98s

before:

    hyperfine "/srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/shared/python2.7/60364a13cc977dd5a894e0239ac889b9/bin/python2.7 /srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/soft/c63ba7265399450b28f9ea6d5667a5e7/bin/buildout -U"
    Benchmark #1: /srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/shared/python2.7/60364a13cc977dd5a894e0239ac889b9/bin/python2.7 /srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/soft/c63ba7265399450b28f9ea6d5667a5e7/bin/buildout -U
      Time (mean ± σ):      2.837 s ±  0.275 s    [User: 2.481 s, System: 0.285 s]
      Range (min … max):    2.482 s …  3.222 s    10 runs

after:

    hyperfine "/srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/shared/python2.7/60364a13cc977dd5a894e0239ac889b9/bin/python2.7 /srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/soft/c63ba7265399450b28f9ea6d5667a5e7/bin/buildout -U"
    Benchmark #1: /srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/shared/python2.7/60364a13cc977dd5a894e0239ac889b9/bin/python2.7 /srv/slapgrid/slappart4/srv/slapos/inst/slappart0/tmp/soft/c63ba7265399450b28f9ea6d5667a5e7/bin/buildout -U
      Time (mean ± σ):      1.875 s ±  0.067 s    [User: 1.660 s, System: 0.148 s]
      Range (min … max):    1.816 s …  2.038 s    10 runs

See merge request !846

Changes configuration files to run repman tests in python3.

Adds the newly added to nexedi's repositories rubygemsrecipe (https://lab.nexedi.com/nexedi/rubygemsrecipe) to the list of tested eggs.

This also fixes rpath of rust binaries.

See merge request nexedi/slapos!845

When proftpd software release is tested locally, the socket named /srv/slapgrid/slappart76/srv/runner/instance/slappart1/tmp/soft/91d420e3970a2088e648d2eb86e155ea/parts/prof is created but never removed.
First it is not an appropriated directory to create a socket and then not removing this socket leads to an error if tests are run a second time :

subprocess.CalledProcessError: Command '('ldd', '/srv/slapgrid/slappart76/srv/runner/instance/sla
ppart1/tmp/soft/91d420e3970a2088e648d2eb86e155ea/parts/prof')' returned non-zero exit status 1.

----------------------------------------------------------------------
Ran 0 tests in 9.914s

FAILED (errors=1)

This is due to code in https://github.com/proftpd/proftpd/blob/master/src/ctrls.c :

const char *socket_path = PR_RUN_DIR "/test.sock"; // socket_path="/srv/slapgrid/slappart76/srv/runner/instance/slappart1/tmp/soft/91d420e3970a2088e648d2eb86e155ea/parts/proftp/var/test.sock"
sstrncpy(sockun.sun_path, socket_path, sizeof(sockun.sun_path)); // sockun.sun_path="/srv/slapgrid/slappart76/srv/runner/instance/slappart1/tmp/soft/91d420e3970a2088e648d2eb86e155ea/parts/prof"

where `sun_path` is limited to UNIX_PATH_MAX (108 characters): char sun_path[UNIX_PATH_MAX]; https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/un.h#L9

See merge request !838

We don't plan using varnish like this.

See merge request !836

stop-on-error during instantiation can lead to endless instantiation in some
cases, which disallows to create services required for given part to pass, and
in the same time in many cases the called scripts are smart enough to continue
and restart on error.

Thanks to this, it's much easier to find relevant configuration, and also logs
are becoming much more informative.

Avoid creating needless entries and minimise needless newlines, and reflect
this in test data, as in such case no backend_log is created, as nothing is
configured on backend Haproxy level.