Eliminate Point2Grid warning when no valid output data is found

[JohnHalleyGotway]

Describe the Enhancement

As requested in the dtcenter/METplus#2738 discussion, eliminate the warning message printed by the Point2Grid tool when no valid data is written to the output. Generally speaking, warnings are written by the MET tools to alert users of unexpected behavior. The situation described by @Ho-ChunHuang-NOAA, that Point2Grid should expect little to no high quality observed AOD during overnight hours means that no valid output values really can be expected outcome.

In order to satisfy NCO requirements to minimize or eliminate warning messages entirely, recommend modifying that log message to report it as DEBUG(2) log level rather than a warning message.

Time Estimate

~2 hours

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None needed

Relevant Deadlines

Include in MET-12.0.0-rc1 release to be available for EVS v2.0.

Funding Source

Need to confirm: 2783544 NOAA R2O METplus

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