Bug 1899328 - Mark dom/base/use_counter_metrics.yaml as generated r=chutten

Differential Revision: https://phabricator.services.mozilla.com/D211872

tools/rewriting/Generated.txt

@@ -18,6 +18,7 @@ browser/locales/l10n-onchange-changesets.json
 devtools/client/aboutdebugging/test/jest/node_modules/
 devtools/client/application/test/components/node_modules/
 devtools/client/debugger/node_modules/
+dom/base/use_counter_metrics.yaml
 dom/tests/ajax/jquery/
 dom/tests/ajax/mochikit/
 intl/components/src/UnicodeScriptCodes.h