Need to correct history file suffixes for test runs

[alperaltuntas]

When TEST=True, the diag_table output frequency is set to 1 day, but the file suffix remains 4yr-%2mo, which means that the history files are constantly overriden at each day, and only including the final day of the run. This should be corrected either by:

• writing out history files for only the last day of the test runs, OR,
• writing out history files for all of the days (which is probably an overkill, causing an unnecessary slowdown.)

Thanks to @jedwards4b for noticing this issue.

[mnlevy1981]

writing out history files for all of the days (which is probably an overkill, causing an unnecessary slowdown.)

I think the default option should be only writing output on the last day, but a mechanism to write history files every day would be great for #167