Merge bitcoin/bitcoin#26961: ci: Fix APPEND_APT_SOURCES_LIST trying to modify the host system

fa88d42 ci: Fix APPEND_APT_SOURCES_LIST trying to modify the host system (MarcoFalke)

Pull request description:

  `>>` will be redirected to the host system, unless the CI system is already running in docker.

  This shouldn't lead to any issues, unless someone is running the CI as root, I guess.

  Still, fix it to avoid problems.

ACKs for top commit:
  fanquake:
    ACK fa88d42

Tree-SHA512: 6c501fd69a62e3cea27d24647e1a02f0f63dad45737dbfed23e3f70d89aacfbe477c71ca8812a47ab4641a31288df5919512542d5d8b49fc57dc3ef2aa0cde33

Author: MarcoFalke

ci/test/04_install.sh

@@ -93,7 +93,7 @@ elif [ "$CI_USE_APT_INSTALL" != "no" ]; then
     CI_EXEC_ROOT add-apt-repository ppa:hadret/bpfcc
   fi
   if [[ -n "${APPEND_APT_SOURCES_LIST}" ]]; then
-    CI_EXEC_ROOT echo "${APPEND_APT_SOURCES_LIST}" >> /etc/apt/sources.list
+    CI_EXEC_ROOT echo "${APPEND_APT_SOURCES_LIST}" \>\> /etc/apt/sources.list
   fi
   ${CI_RETRY_EXE} CI_EXEC_ROOT apt-get update
   ${CI_RETRY_EXE} CI_EXEC_ROOT apt-get install --no-install-recommends --no-upgrade -y "$PACKAGES" "$CI_BASE_PACKAGES"