Remove country code check from thunderbird android baseline_clients_last_seen

sql/moz-fx-data-shared-prod/net_thunderbird_android_derived/baseline_clients_last_seen_v1/checks.sql

@@ -26,9 +26,6 @@ FROM
 WHERE
   submission_date = @submission_date;
 
-#warn
-{{ matches_pattern(column="country", pattern="^[A-Z]{2}$", where="submission_date = @submission_date") }}
-
 #warn
 {{ value_length(column="client_id", expected_length=36, where="submission_date = @submission_date") }}