Fix for array index out of bounds

[Chsudeepta]

Description of work

This PR fixes the ticket

To replicate the issue, go to DAE screen, "Experiment Setup" Tab and click on the "Periods" subtab.

Acceptance criteria

• The code should follow the coding standards
• The array index out of bounds shouldn't come when DAE experiment setup is done
• Code should build without errors including checkstyle issues.

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Code Review

• Is the code of an acceptable quality?
• If the change is to an OPI, does the check_opi_format.py script in C:\Instrument\Dev\ibex_gui\base\uk.ac.stfc.isis.ibex.opis pass?
• Do the changes function as described and is it robust?

Final Steps

[iangillingham-stfc]

The changes in this PR look correct and it's surprising it ever worked, given that thet rowIndex was reset on every iteration.
As a general comment, table.getColumnCount() is being called repeatedly, it would be better to call it once at the beginning and store the value in a local stack variable.