Convert the high_level_api to logger, and update warning for xlsx export
warnings.simplefilter does not suppress warnings from import calls (probably same as this), which makes workarounds necessary to suppress the 'api unstable' warning emitted during import of the high_level_api.
Fix by instead using the logger.warning method to warn, and test that the warning can be suppressed by suppressing it in the xlsx export.
MRs: