Removed the merge-train script

We're moving the automatic merging logic to a separate repository, so
there's no need in keeping this file around.

[ci skip]

scripts/merge-train

-#!/bin/sh
-
-set -e
-
-# The name (including namespace) of the EE repository to merge commits into.
-EE_PROJECT='gitlab-org/gitlab-ee'
-
-# The directory to clone GitLab EE into.
-EE_DIRECTORY="$CI_PROJECT_DIR/gitlab-ee"
-
-# The EE branch to merge the changes into.
-EE_BRANCH='master'
-
-# Runs an incremental or periodic merge of CE to EE. This script should be run
-# from a container built using https://gitlab.com/gitlab-org/merge-train.
-
-# Merges (or reverts) commits in a batch (based on CI_COMMIT_BEFORE_SHA and
-# CI_COMMIT_SHA), or since a specific commit.
-#
-# The optional first argument of this function should be a SHA of a commit. When
-# specified, all commits since this commit will be processed.
-merge() {
-    # We need to source the configure-ssh script instead of running it with
-    # `sh`, since it uses `eval` for SSH agent and we want the result of that to
-    # persist.
-    #
-    # shellcheck disable=SC1091
-    . /app/bin/configure-ssh
-
-    # We can not perform a shallow clone, as this results in Git sometimes
-    # refusing to fetch from CE. To work around this, we perform a full clone
-    # but cache the repository in CI. If a cached repository exists, we simply
-    # just pull from `master`.
-    if [ -d "$EE_DIRECTORY" ]
-    then
-        echo "Updating existing clone of $EE_PROJECT"
-
-        git -C "$EE_DIRECTORY" pull --quiet origin "$EE_BRANCH"
-    else
-        echo "Cloning $EE_PROJECT"
-
-        git clone --quiet --single-branch --branch "$EE_BRANCH" \
-            "git@gitlab.com:$EE_PROJECT.git" "$EE_DIRECTORY"
-    fi
-
-    cd /app
-
-    env GITLAB_TOKEN="$MERGE_TRAIN_API_TOKEN" \
-        bundle exec /app/bin/merge-train "$CI_PROJECT_DIR" "$EE_DIRECTORY" \
-        --source-name "$CI_PROJECT_PATH" \
-        --target-branch "$EE_BRANCH" \
-        ${1:+--before "$1"}
-}
-
-# Merges (or reverts) all commits since a point in time as supported by `git log
-# --since`, such as "12 hours ago".
-merge_since() {
-    commit="$(git log --since="$MERGE_SINCE" --reverse --format=%H | head -n1)"
-
-    if [ "$commit" = '' ]
-    then
-        echo "There are no commits to merge since $MERGE_SINCE"
-    else
-        merge "$commit"
-    fi
-}
-
-if [ "$MERGE_SINCE" ]
-then
-    merge_since
-else
-    merge
-fi