Use reproducibility flags for Gadi

[penguian]

Document the reproducibility flags that were used in testing https://github.com/penguian/1deg_jra55_ryf migration from NCI Raijin to Gadi.

Using these flags with the Intel 2019.3.199 compilers produced identical output on Raijin and Gadi. See "repro group 4" in the report summary for results.