config: bugfix in parsing per-country configuration fils

Bugfix in evaluating filename containing than 2 specifier.
e.g. cal-<sku>-<country>.conf

Bug: 403506578
Test: check cal-<sku>-<country>.conf from country code switching
Change-Id: I6eb3e8c08871d06f16824fab4b6c6720f74bc77f