Update Attribute Table after field calculation: fixes #17312

[luipir]

Description

The attribute table is not updated because listener of endEditCommand does no more reload masterModel to avoid change row postion during editing.
This patch reload masterModel explicitly as done in other part of the same code.
Port to 3.x of 2.18 PR #5433

Checklist

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[luipir]

I can't find a way to test it. I don't find a way to get the value of the QgsAttributeTableView at a specified index other than getting the value from masterModel.
But masterModel is not aligned with the view if the reload is not executed. So I need to test the difference among the model and the view.

somethig like

  // run length calculation
  std::unique_ptr< QgsAttributeTableDialog > dlg( new QgsAttributeTableDialog( tempLayer.get() ) );
  dlg->mMainView->setView( QgsDualView::AttributeTable );

  tempLayer->startEditing();
  dlg->runFieldCalculation( tempLayer.get(), QStringLiteral( "col1" ), QStringLiteral( "$length" ) );
  // before commit chage check if masterModel has been update and related attribute table view
  QSettings s;
  s.setValue( QStringLiteral( "/qgis/attributeTableBehavior" ), QgsAttributeTableFilterModel::ShowAll );
  double expected = 26932.156;
  QModelIndex index = dlg->mMainView->tableView()->model()->index( 0, 1 );
  QVERIFY( index.isValid() );
  QGSCOMPARENEAR( index.data().toDouble(), expected, 0.001 );

[elpaso]

@m-kuhn I see you merged the 2.18 backport, can we merge this for master too? (I didn't review)

[m-kuhn]

Yes, thanks