How to remedy candlepin connection leak together with its root cause in Satellite 6.3?

Issue

• various services (usually pulp) fail to connect to qpidd due to connection limitin qpidd reached
  • increasing this limit just ppostpones the error but does not resolve it
• java / candlepin has excessive number of connections to qpidd (usually there should be just one)
• candlepin is (often) in suspended mode