Remove duplicate key check in cacheCommandOutput and related tests

This key-check is unnecessary because this function is only ever called if the key does NOT exist in the cache already. In that case, why check again?

lib/entry-points.js

@@ -149942,11 +149942,6 @@ function writeCommandCacheFile(data) {
   }
 }
 function cacheCommandOutput(key, cmd, output) {
-  if (inMemoryCache.has(key)) {
-    throw new Error(
-      `cacheCommandOutput() should be called only once per key, but was called more than once for '${key}'.`
-    );
-  }
   const entry = { cmd, output };
   inMemoryCache.set(key, entry);
   const data = readCommandCacheFile();