Fix read of PB2NC window configuration variables

[georgemccabe]

This was discovered in discussion #1484. More details can be found there.

Describe the Problem

Fix logic so that the following METplus config variables are read properly:
PB2NC_FILE_WINDOW_BEGIN
PB2NC_FILE_WINDOW_END
PB2NC_WINDOW_BEGIN
PB2NC_WINDOW_END

Expected Behavior

Provide a clear and concise description of what you expected to happen here.

Environment

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1. Machine: (e.g. HPC name, Linux Workstation, Mac Laptop)
2. OS: (e.g. RedHat Linux, MacOS)
3. Software version number(s)

To Reproduce

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1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error
Post relevant sample data following these instructions:
https://dtcenter.org/community-code/model-evaluation-tools-met/met-help-desk#ftp

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Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy

Bugfix Checklist

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• Close this issue.

[georgemccabe]

Re-open this issue if a bugfix patch should be applied to main_v4.0 so that it is available for 4.0.X