tests and compatible with CI.

Modified MysqlCatalogue.cpp to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Please note that neither setAutcommitMode() and getAutcommitMode()
should be called for now.  This commit is preparing the future
interface of the code.

Modified RdbmsArchiveFileItorImpl.cpp to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Modified DropSchemaCmd to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Modified CreateSchemaCmd to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Modified RdbmsCatalogue to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Please note that OracleCatalogue::filesWrittenToTape() now updates the TAPE
table row with AUTOCOMMIT_ON before going on to handle the individual file
entries.  This can be improved when Conn:setAutocommit() becomes available.

Moved the getPoppingElementsCandidates() method from RetrieveQueueFailedAlgorithms, RetrieveQueueToTransferAlgorithms and RetrieveQueueToReportToRepackForSuccessAlgorithms into RetrieveQueueAlgorithms
This removed the duplication of the code in this method repeated 3 times

Set default value of autocommitMode parameter of executeQuery() and executeNonQuery() to AutocommitMode::AUTOCOMMIT_ON

Conflicts:
	scheduler/SchedulerTest.cpp

Changed the return type of scheduler.getNextSucceededRetrieveRequestForRepackBatch() method from cta::SchedulerDatabase::RetrieveJob to cta::RetrieveJob

The getNextSucceededRetrieveRequestForRepackBatch is implemented and integrated in the expandRepackRequest test

Started to implement the method to get the RetrieveRequest from the RetrieveQueueToReportToSuccessForRepack queue

Conflicts:
	xrootd-ssi-protobuf-interface

Refactored OStoreDB::RetrieveMount::batchSucceedRetrieveForRepack() method

Make was interpreting the variable instead of the underlying shell

-> Moved code related to payload manipulation in the cta::objectstore::RetrieveRequest class

Changed the operator "<" of Scheduler::PotentialMount so that the sorting of mounts is in alphabetical order

This was a rare occurence:
Tue Jan 29 01:12:51 2019 pid=531 tid=951 op=In BackendRados::lockBackoff(): radosCtx.lock_exclusive() obj=Frontend-ctafrontend-531-20190128-18:02:44-0 duration=51.5958

(One out of 5 operations taking more than 1s in the whole day.