fix: Fix and rename pg_database_url.sh helper script (#2747)

- Fix and rename pg_database_url helper script
- Use single-quote and remove trailing whitespace

docker/entrypoints/helpers/pg_database_url.rb

@@ -0,0 +1,10 @@
+#!/usr/bin/env ruby
+require 'uri'
+
+# Let DATABASE_URL env take presedence over individual connection params.
+if !ENV['DATABASE_URL'].nil? && ENV['DATABASE_URL'] != ''
+  uri = URI(ENV['DATABASE_URL'])
+  puts "export POSTGRES_HOST=#{uri.host} POSTGRES_PORT=#{uri.port} POSTGRES_USERNAME=#{uri.user}"
+elsif ENV['POSTGRES_PORT'].nil? || ENV['POSTGRES_PORT'] == ''
+  puts 'export POSTGRES_PORT=5432'
+end