Bugfix 2123 main v10.1 nccf valid time

[hsoh-u]

Expected Differences

The problem was caused by the int64 type time variable which was not supported yet.
Before: time information was not from valid_time variable which has the standard_name = "time"

DEBUG 4: Data plane information:
DEBUG 4:    plane min: 0
DEBUG 4:    plane max: 2.10354
DEBUG 4:    valid time: 19700101_000000
DEBUG 4:    lead time: 000000
DEBUG 4:    init time: 19700101_000000
DEBUG 4:    accum time: 000000

after supporting int64 data type:

DEBUG 4: Data plane information:
DEBUG 4:    plane min: 0
DEBUG 4:    plane max: 2.10354
DEBUG 4:    valid time: 20220221_000000
DEBUG 4:    lead time: 000000
DEBUG 4:    init time: 20220221_000000
DEBUG 4:    accum time: 000000

• Do these changes introduce new tools, command line arguments, or configuration file options? [No]
  
  If yes, please describe:
  

• Do these changes modify the structure of existing or add new output data types (e.g. statistic line types or NetCDF variables)? [No]
  
  If yes, please describe:
  

Pull Request Testing

• Describe testing already performed for these changes:
  

The input data exists at #2123
plot_data_plane obs.nc obs.ps 'name="precipitation"; level="(,)";' -title "Observation precipitation" -v 4
OR
/d1/personal/hsoh/git/bugfixes/bugfix_2123_main_v10.1_nccf_valid_time/MET/met/bin/plot_data_plane /d1/personal/hsoh/data/MET-2123/obs.nc obs.ps 'name="precipitation"; level="(,)";' -title "Observation precipitation" -v 4

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  

The same test

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [No]

• Do these changes include sufficient testing updates? [No]

• Will this PR result in changes to the test suite? [No]
  
  If yes, describe the new output and/or changes to the existing output:
  

• Please complete this pull request review by [Fill in date].
  

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[JohnHalleyGotway]

I approve of these changes. I ran the test indicated on seneca and confirmed the expected result.