Fix intel debug warnings (implicit i,j,k; explicit mpi interface)

[NickSzapiro-NOAA]

Description

One round of straight-forward fixes for some of the compiler warnings raised in compiling cpld_debug_gfsv17 to improve code quality and prepare for operational implementation

Part of ufs-community/ufs-weather-model#2703

How Has This Been Tested?

Tested via ufs-weather-model RTs and compile err logs with Intel and GNU compilers on Ursa

Checklist:

Please check all whether they apply or not

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[gspetro-NOAA]

If there are atmos_cubed_sphere code managers available to approve this PR, it would be very helpful. The parent WM PR #2935 needs to be processed soon for GFS v17 retros.

[JosephMouallem]

great catch, we could also fix this in the main branch.