BatchOperations::assembleRows blindly calls getTotalItemCount

Problem/Motivation

When BatchOperations::assembleRows is called to build the List of BatchOperations in the UI it blindly calls $script->getTotalItemCount(); which gathers the items to be processed (could be an intensive gathering)
but then in buildCompleteStatus() it only uses that value if there is no BatchOpLog from a previous run.

There are two options

1. Remove this early call and only call if needed.
2. Keep the early call, but do something with the value, like identify if the last run shows a completion number that does not match the currently count.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes