Merge bitcoin#31146: ci: Temporary workaround for old CCACHE_DIR cirrus env

fa9747a ci: Temporary workaround for old CCACHE_DIR cirrus env (MarcoFalke)

Pull request description:

  On a CI re-run, the historic env vars and CI config is used from Cirrus. However, the most recent CI config and CI scripts from this repo are used. This may lead to issues.

  For example, `CCACHE_DIR` in the old location may be missing on new CI workers and lead to errors.

  Fix it, by falling back to the old logic when the old `CCACHE_DIR` was detected.

ACKs for top commit:
  fanquake:
    ACK fa9747a - have seen this now.

Tree-SHA512: 04f0ca8d09ab0b8216a474fde1e05b79fbc6524884be173e8d728799739b026cda18d1797e0fe53d7e1b0ea69c0485acfe4f8a8f85408ea5bfdcffcf13a7ce55

Author: fanquake

ci/test/02_run_container.sh

@@ -59,11 +59,16 @@ if [ -z "$DANGER_RUN_CI_ON_HOST" ]; then
   fi
 
   if [ "$DANGER_CI_ON_HOST_CCACHE_FOLDER" ]; then
+   # Temporary exclusion for https://github.com/bitcoin/bitcoin/issues/31108
+   # to allow CI configs and envs generated in the past to work for a bit longer.
+   # Can be removed in March 2025.
+   if [ "${CCACHE_DIR}" != "/tmp/ccache_dir" ]; then
     if [ ! -d "${CCACHE_DIR}" ]; then
       echo "Error: Directory '${CCACHE_DIR}' must be created in advance."
       exit 1
     fi
     CI_CCACHE_MOUNT="type=bind,src=${CCACHE_DIR},dst=${CCACHE_DIR}"
+   fi # End temporary exclusion
   fi
 
   docker network create --ipv6 --subnet 1111:1111::/112 ci-ip6net || true