Bug 1896463 - Raise an exception if generating partials tasks for an unknow platform r=releng-reviewers,taskgraph-reviewers,bhearsum

Differential Revision: https://phabricator.services.mozilla.com/D210224

taskcluster/gecko_taskgraph/util/partials.py

@@ -76,8 +76,6 @@ def get_balrog_platform_name(platform):
 
 def _sanitize_platform(platform):
     platform = get_balrog_platform_name(platform)
-    if platform not in BALROG_PLATFORM_MAP:
-        return platform
     return BALROG_PLATFORM_MAP[platform][0]