fix(tests): update database connection strings for CI

* Use dynamic host and port for Postgres in tests
* Add helper functions for test database host and port

tests/integration/connection_test.go

@@ -2,6 +2,7 @@ package integration
 
 import (
 	"database/sql"
+	"fmt"
 	"testing"
 	"time"
 
@@ -10,7 +11,7 @@ import (
 )
 
 func TestConnection(t *testing.T) {
-	connStr := "user=user password=password dbname=broker_test host=127.0.0.1 port=5433 sslmode=disable"
+	connStr := fmt.Sprintf("user=user password=password dbname=broker_test host=%s port=%d sslmode=disable", testDBHost(), testDBPort())
 	var db *sql.DB
 	var err error