Merge topic 'ci-inplace'

b88f7aad63 ci: add nightly CI job to build CMake in-place
2a7ac62c04 ci: Compute processor count earlier in ctest_standalone.cmake
1613d87dee ci: Rename ctest_test_external.cmake to ctest_standalone.cmake
ac37e99453 ci: Rename variable CMake_SKIP_INSTALL to CMAKE_CI_NO_INSTALL

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !7033