Merge topic 'ci-valgrind'

e981fc4f4d gitlab-ci: add a job to test with Valgrind on Linux with Ninja
f1e8762a8b ci: support valgrind memcheck runs
f22d8a3f36 ci: support memcheck-testing external test processes
35337bcc06 gitlab-ci: report JUnit results for memcheck runs
8459ff022b ci: factor out memcheck "prep" logic

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !11257