ci: speed up CI using multiple processes with pylint and pytest (#67080)

Jenkinsfile

@@ -9,7 +9,7 @@ pipeline {
     stages {
         stage('Unit Tests') {
             steps {
-                sh 'tox -rv'
+                sh 'NUMPROCESSES=6 tox -rv '
             }
             post {
                 always {

pylint.sh

@@ -1,5 +1,4 @@
 #!/bin/bash
 set -e -x
 env
-
-pylint -f parseable --rcfile pylint.rc "$@" | tee pylint.out; test $PIPESTATUS -eq 0
+pylint --jobs ${NUMPROCESSES:-1} -f parseable --rcfile pylint.rc "$@" | tee pylint.out; test $PIPESTATUS -eq 0

tox.ini

@@ -10,6 +10,7 @@ setenv =
   BRANCH_NAME={env:BRANCH_NAME:}
   WCSCTL=wcs/wcsctl.py
   SETUPTOOLS_USE_DISTUTILS=stdlib
+  NUMPROCESSES={env:NUMPROCESSES:1}
   fast: FAST=--nomigrations
   coverage: COVERAGE=--junitxml=junit-{envname}.xml --cov-report xml --cov-report html --cov=passerelle/ --cov-config .coveragerc -Wignore
 deps =
@@ -19,6 +20,7 @@ deps =
   psycopg2-binary<2.9
   pytest-cov
   pytest-django
+  pytest-xdist
   pytest!=6.0.0
   WebTest
   mock<4
@@ -41,7 +43,7 @@ deps =
   codestyle: pre-commit
 commands =
   ./get_wcs.sh
-  py.test {posargs: {env:FAST:} {env:COVERAGE:} {env:JUNIT:} tests/}
+  py.test {posargs: --numprocesses {env:NUMPROCESSES:1} --dist loadfile {env:FAST:} {env:COVERAGE:} {env:JUNIT:} tests/}
   codestyle: pre-commit run --all-files --show-diff-on-failure
 
 [pytest]
@@ -60,6 +62,7 @@ setenv =
   PASSERELLE_SETTINGS_FILE=tests/settings.py
   BRANCH_NAME={env:BRANCH_NAME:}
   SETUPTOOLS_USE_DISTUTILS=stdlib
+  NUMPROCESSES={env:NUMPROCESSES:6}
 deps =
   pytest-django
   pytest!=6.0.0