Fix typo in host.ts (microsoft#43930)

encounted -> encountered

Author: Ikko Ashimine

src/testRunner/parallel/host.ts

@@ -285,7 +285,7 @@ namespace Harness.Parallel.Host {
                 worker.process.on("message", (data: ParallelClientMessage) => {
                     switch (data.type) {
                         case "error": {
-                            console.error(`Test worker encounted unexpected error${data.payload.name ? ` during the execution of test ${data.payload.name}` : ""} and was forced to close:
+                            console.error(`Test worker encountered unexpected error${data.payload.name ? ` during the execution of test ${data.payload.name}` : ""} and was forced to close:
             Message: ${data.payload.error}
             Stack: ${data.payload.stack}`);
                             return process.exit(2);