ci: add a small script one can run to purge older pipeline

We have over ten thousands old pipeline that take a huge space and that I
suspect to be the source of some slowdown in merge request.

However it seems that the only way to clear them is manually and through the
API, so lets do it.

The script was run today.

contrib/cleanup-pipeline.sh

@@ -0,0 +1,36
+#!/bin/bash
+# A small script to cleanup old CI-pipeline that accumulate over time
+
+
+d="`date -d '-1 month' --iso-8601`T00:00:00Z"
+
+PROJECT_ID=22
+
+token=$1
+
+if [ -z $token ]; then
+    echo "USAGE: $0 GITLAB_TOKEN" >&2
+    exit 64
+fi
+
+get_ids() {
+    curl --silent "https://foss.heptapod.net/api/v4/projects/$PROJECT_ID/pipelines?updated_before=$d&per_page=100" | python3 -m json.tool | grep -E '"\bid": ([0-9]+),' | grep -oE '[0-9]+'
+}
+
+ids=`get_ids`
+while [ -n "$ids" ]; do
+    echo '#########'
+    for pipeline_id  in $ids; do
+        echo "deleting pipeline #$pipeline_id"
+        url="https://foss.heptapod.net/api/v4/projects/$PROJECT_ID/pipelines/$pipeline_id"
+        echo $url
+        curl \
+            --header "PRIVATE-TOKEN: $token"\
+            --request "DELETE"\
+            $url
+    done
+    ids=`get_ids`
+    if [ -n "$ids" ]; then
+        sleep 1
+    fi
+done