Remove old caching stuff from CI (#1154)

scripts/ci/pre_cache.sh

@@ -1,28 +0,0 @@
-#!/bin/bash
-
-set -u
-
-# if there is no directory for this $CI_COMMIT_REF_NAME/$CI_JOB_NAME
-# create such directory and
-# copy recursively all the files from the newest dir which has $CI_JOB_NAME, if it exists
-
-# cache lives in /ci-cache/${CI_PROJECT_NAME}/${2}/${CI_COMMIT_REF_NAME}/${CI_JOB_NAME}
-
-function prepopulate {
-  if [[ ! -d $1 ]]; then
-    mkdir -p "/ci-cache/$CI_PROJECT_NAME/$2/$CI_COMMIT_REF_NAME";
-    FRESH_CACHE=$(find "/ci-cache/$CI_PROJECT_NAME/$2" -mindepth 2 -maxdepth 2 \
-      -type d -name "$CI_JOB_NAME"  -exec stat --printf="%Y\t%n\n" {} \; |sort -n -r |head -1 |cut -f2);
-    if [[ -d $FRESH_CACHE ]]; then
-      echo "____Using" "$FRESH_CACHE" "to prepopulate the cache____";
-      time cp -r "$FRESH_CACHE" "$1";
-    else
-      echo "_____No such $2 dir, proceeding from scratch_____";
-    fi
-  else
-    echo "____No need to prepopulate $2 cache____";
-  fi
-}
-
-# CARGO_HOME cache is still broken so would be handled some other way.
-prepopulate "$CARGO_TARGET_DIR" targets