Bugfix: Fix inconsistent handling of point observation valid times processed through Python embedding

Describe the Problem

The METplus Point-Stat TCI Use Case recently produced unexpected differences when run via GitHub Actions. Careful investigation by @DanielAdriaansen (documented here) showed the following:

Re-create the dtcenter/METbaseimage v3.2 release triggered these differences.
The updated image lead to the Python glob serving up files to a MET Python embedding script in a different order.
The different order of input files lead to a different order of point observations being served up in memory to Point-Stat.
A bug in how valid time strings are stored for Python embedding of point observations produced different results from Point-Stat. Specifically, the observation are filtered by their valid time in an inconsistent way.

Expected Behavior

The order of point observations served up via Python embedding to Point-Stat should have no impact on filtering by valid time.

To Reproduce

Describe the steps to reproduce the behavior:

Download this sample data file: issue_2897_data.tar.gz
Unpack the file and update the MET_BIN setting in run_ps.sh to point to a local MET binary directory.
Execute run_ps.sh.

The following command:

for OBS_SID in `cat out_test2/point_stat_000000L_19790101_000000V_mpr.txt | awk '{print $27}'`; do
grep $OBS_SID test1.csv;
grep $OBS_SID test2.csv;
echo "$OBS_SID test1: `grep $OBS_SID out_test1/point_stat_000000L_19790101_000000V_mpr.txt | awk '{print $8, $28, $29}'`";
echo "$OBS_SID test2: `grep $OBS_SID out_test2/point_stat_000000L_19790101_000000V_mpr.txt | awk '{print $8, $28, $29}'`";
echo;
done

Note the following timestamp mismatch:

ADPSFC CH-Oe1 20020128_000000 47.2858 7.7319 10 TCI 10 0 NA 1.1331664358420377
CH-Oe1 test1: 20020128_000000 47.2858 7.7319
CH-Oe1 test2: 20051201_000000 47.2858 7.7319

In test2, the timestamp for CH-Oe1 is WRONG.

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Define Related Issue(s)

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[ ] METplus, MET, METdataio, METviewer, METexpress, METcalcpy, METplotpy

Bugfix Checklist

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[ ] Complete the issue definition above, including the Time Estimate and Funding Source.
[ ] Fork this repository or create a branch of main_\. Branch name: bugfix_<Issue Number>_main_<Version>_<Description>
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dtcenter / MET