Implemented new interface to Job Transforms for activating MT and MP jobs

As it was described in the How to run multi-core jobs in production document and in ATLASJT-403, we are introducing two command-line options for the job transform:

• --multithreaded
• --multiprocess

As the names suggest, the former is used for running AthenaMT and the latter for running AthenaMP. The number of threads/processes is taken from a new ATHENA_CORE_NUMBER environment variable.

Now, we have two equivalent ways to run a job in AthenaMT (Reco_tf is used here as an example):

ATHENA_CORE_NUMBER=N Reco_tf.py --multithreaded [Other Options]
Reco_tf.py --athenaopts=--threads=N [Other Options]

Similarly, for running AthenaMP we have two options:

ATHENA_CORE_NUMBER=N Reco_tf.py	--multiprocess [Other Options]
Reco_tf.py --athenaopts=--nprocs=N [Other Options]

We will get a configuration error from the transform if one of the following occurs:

• ATHENA_CORE_NUMBER is set but neither --multiprocess nor --multithreaded option was provided.
• ATHENA_CORE_NUMBER was not set but either --multiprocess or --multithreaded was provided
• Both --multiprocess and --multithreaded options were provided to the same job
• --multiprocess was used in combination with either --athenaopts=--nprocs=N or --athenaopts=--threads=N
• --multithreaded was used in combination with --athenaopts=--threads=N or --athenaopts=--nprocs=N

By implementing these changes we declare the old ATHENA_RPOC_NUMBER environment obsolete. Athena repository has been cleaned up from the dependency on this environment. The only exception is Generator code, which is yet to be migrated.

Tag: @emoyse @wlampl @ssnyder @leggett @fwinkl @akraszna @girolamo @elmsheus @tmaeno @pnilsson @walker @mavogel (please feel free to forward this MR to other interested people).