Salsa-CI: Extend crossbuild to build armhf and armel as well

Last time cross-build to arm64 worked on debian/latest (Feb 3rd, 2024): https://salsa.debian.org/mariadb-team/mariadb-server/-/jobs/5248961

Previous time cross-build to arm64 went a bit further on debian/latest: https://salsa.debian.org/mariadb-team/mariadb-server/-/jobs/5357089

Status April 30th, 2024

Currently failing on the same issue as crossqa.debian.net. Compare last passing https://crossqa.debian.net/build/mariadb_1:10.11.6-2_arm64_20240106230126.log and latest https://crossqa.debian.net/build/mariadb_1:10.11.7-4_arm64_20240414143344.log:

-- Performing Test HAVE_SYSTEM_LIBFMT
CMake Error: try_run() invoked in cross-compiling mode, please set the following cache variables appropriately:
   HAVE_SYSTEM_LIBFMT_EXITCODE (advanced)
For details see /<<PKGBUILDDIR>>/builddir/TryRunResults.cmake
-- Performing Test HAVE_SYSTEM_LIBFMT - Failed