refactor: use frontend instead of plural

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

unit_test/main_tests/main_options_test.py

@@ -283,13 +283,13 @@ def test_config_settings(platform_specific, platform, intercepted_build_args, mo
 
     assert build_options.config_settings == config_settings
 
-    assert split_config_settings(config_settings, plural=False) == [
+    assert split_config_settings(config_settings, "build") == [
         "--config-setting=setting=value",
         "--config-setting=setting=value2",
         "--config-setting=other=something else",
     ]
 
-    assert split_config_settings(config_settings, plural=True) == [
+    assert split_config_settings(config_settings, "pip") == [
         "--config-settings=setting=value",
         "--config-settings=setting=value2",
         "--config-settings=other=something else",