chore: add tests for postgre backend with tls (#6973)

* chore: add tests for postgre backend with tls

Signed-off-by: WenyXu <wenymedia@gmail.com>

* chore: minor

Signed-off-by: WenyXu <wenymedia@gmail.com>

* chore: apply suggestions

Signed-off-by: WenyXu <wenymedia@gmail.com>

---------

Signed-off-by: WenyXu <wenymedia@gmail.com>

scripts/generate_pgsql_certs.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+CERT_DIR="${1:-$(dirname "$0")/../tests-integration/fixtures/pgsql-certs}"
+DAYS="${2:-365}"
+
+mkdir -p "${CERT_DIR}"
+cd "${CERT_DIR}"
+
+echo "Generating CA certificate..."
+openssl req -new -x509 -days "${DAYS}" -nodes -text \
+  -out root.crt -keyout root.key \
+  -subj "/CN=PostgresRootCA"
+
+
+echo "Generating server certificate..."
+openssl req -new -nodes -text \
+  -out server.csr -keyout server.key \
+  -subj "/CN=postgres"
+
+openssl x509 -req -in server.csr -text -days "${DAYS}" \
+  -CA root.crt -CAkey root.key -CAcreateserial \
+  -out server.crt \
+  -extensions v3_req -extfile <(printf "[v3_req]\nsubjectAltName=DNS:localhost,IP:127.0.0.1")
+
+echo "Generating client certificate..."
+# Make sure the client certificate is for the greptimedb user
+openssl req -new -nodes -text \
+  -out client.csr -keyout client.key \
+  -subj "/CN=greptimedb"
+
+openssl x509 -req -in client.csr -CA root.crt -CAkey root.key -CAcreateserial \
+-out client.crt -days 365 -extensions v3_req -extfile <(printf "[v3_req]\nsubjectAltName=DNS:localhost")
+
+rm -f *.csr
+
+echo "TLS certificates generated successfully in ${CERT_DIR}"
+
+chmod 600 root.key
+chmod 600 client.key
+chmod 600 server.key