v9.0.0a42

[integration]

*Core

NEW: (#8041) new command dirac-apptainer-exec for running DIRAC commands inside apptainer
FIX: (#8034) Correct user mapping for DiracX from IAM

*WorkloadManagement

FIX: (#8040) get ElasticJobParametersDB index prefix from the configuration
CHANGE: (#8014) Use apptainer for SingularityComputingElement
CHANGE: (#8014) Drop support for SingularityComputingElement without user namespaces
CHANGE: (#8014) Enchance debugging output if SingularityComputingElement fails
CHANGE: (#8014) Drop support for using apptainer from outside of DIRACOS2

*ConfigurationSystem

FIX: (#8040) evaluate useCRT flag as boolean in Utilities.getElasticDBParameters()