Merge bitcoin#30369: ci: Clear unused /msan/llvm-project

fa6beb8 ci: Clear unused /msan/llvm-project (MarcoFalke)

Pull request description:

  Could help to fix the `no space left on device` that are sometimes seen.

ACKs for top commit:
  theuni:
    utACK fa6beb8

Tree-SHA512: 0bedf4b26eed842c7bfa2caeac4df578cdbb00a658e8d0037b8b7b90150d8a9d1b8140437d1cf40b50d82a9085ea50cf9a010764c4439b2a03a457d399191319

ci/test/01_base_install.sh

@@ -65,6 +65,10 @@ if [[ ${USE_MEMORY_SANITIZER} == "true" ]]; then
     -S /msan/llvm-project/runtimes
 
   ninja -C /msan/cxx_build/ "-j$( nproc )"  # Use nproc, because MAKEJOBS is the default in docker image builds
+
+  # Clear no longer needed source folder
+  du -sh /msan/llvm-project
+  rm -rf /msan/llvm-project
 fi
 
 if [[ "${RUN_TIDY}" == "true" ]]; then