feat(dbtest): Mount DB dumps and create templates

Mount the benchmark dump directory when running
the test database and create a new script for creating
templates from the dumps. This makes it easy to create
pre-populated databases for benchmark tests.

Fixes https://hashicorp.atlassian.net/browse/ICU-4040

testing/dbtest/docker/restore-benchmark-dumps.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -e
+shopt -s globstar
+
+for file in $(ls -v /benchmark_dumps/*.dump); do
+    echo "Creating template database based on: ${file}"
+    db_name="boundary_$(basename ${file} .dump)_template"
+    psql -v "ON_ERROR_STOP=1" --username "$POSTGRES_USER" --dbname "${POSTGRES_DB}" -q <<EOSQL
+    create database ${db_name} owner ${POSTGRES_USER};
+EOSQL
+    echo "Restoring ${file} into ${db_name}"
+    pg_restore -j $(nproc) --username "${POSTGRES_USER}" --dbname ${db_name} "${file}"
+    psql -v "ON_ERROR_STOP=1" --username "${POSTGRES_USER}" --dbname "${POSTGRES_DB}" -q <<EOSQL
+    update pg_database set datistemplate = true, datallowconn = false where datname = '${db_name}';
+EOSQL
+done