Make ttgw in gravity wave drag parameterizations consistent

[jimmielin]

During the review of #292

Some gravity wave parameterizations use cpairv to convert to temperature tendency, some use cpair, and some do not do this conversion, when outputting ttgw.

    ! Convert T tendency to K s-1
    ! FIXME: some places use cpairv (e.g., orographic) but cpair is used here. hplin 8/14/25
    ttrdg = ttrdg / cpair

Work has to be done to make these consistent.

When changing from cpair to cpairv, there will be answer changes for the temperature tendency diagnostics for both CAM and CAM-SIMA.

[cacraigucar]

@jimmielin - Will fix this in round2 of gravity wave CCPP'ization work