Correct app_error usage

[ye-luo]

Proposed changes

Address #4681 in a few places.

a) bug fix in Concurrency/ParallelExecutorOPENMP.hpp
b) clean up the MPC class
c) Remove dead ECPComponentBuilder::createVrWithData

What type(s) of changes does this code introduce?

• Bugfix

Does this introduce a breaking change?

• No

What systems has this change been tested on?

epyc-server

Checklist

• Yes. This PR is up to date with current the current state of 'develop'

[ye-luo]

Test this please

[prckent]

Why no longer needed?

[ye-luo]

The current implementation is no-op at line 33

resetTargetParticleSet(qp) {}

and resetTargetParticleSet should go away eventually.

[PDoakORNL]

Why not use UniformCommunicateError?

[PDoakORNL]

As far as using myComm instead of thinking about the scope of error handling I'm not a big fan. I think the right place to catch these sort of errors is at the scope matching a particular communicator. i.e.

qmcapp.cpp 209-:

    if (inputs.size() > 1)
      validInput = qmc->parse(inputs[qmcComm->getGroupID()]);
    else
      validInput = qmc->parse(inputs[0]);

    if (!validInput)
      qmcComm->barrier_and_abort("main(). Input invalid.");

    ...
    qmc.reset()

with

try
{

    if (inputs.size() > 1)
      qmc->parse(inputs[qmcComm->getGroupID()]);
    else
      qmc->parse(inputs[0]);
    ...
    qmc.reset()
}
catch(const UniformCommunicateError& uce)
{
      qmcComm->barrier_and_abort("main(). Input invalid.");

}