.gitlab-ci.yml: Make lcov_artifact and junit artifacts cohabitate

See !289
9 jobs for feature-a/3444-artificats-junit in 41 minutes and 25 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test Tools
passed #171127
test_tools

00:00:05

 
  Test Unit
passed #171128
test_algo_unit

00:02:25

 
  Test Shouldvdj
passed #171129
test_algo_shouldvdj

00:17:42

 
  Test Functional
passed #171130
test_algo_should

00:13:01

 
  Coverage
passed #171131
algo_coverage

00:00:06

88.5%
 
  Prepare Release
manual #171132
allowed to fail manual
prepare_release
 
  Valgrind Unit
passed #171133
valgrind
algo_valgrind_unit

00:08:03

 
  Valgrind Functional
manual #171134
valgrind allowed to fail manual
algo_valgrind_functional
 
  Multiple Tests
manual #171135
several-compilers allowed to fail manual
test_various_compilers_manual