fix(@angular-devkit/benchmark): Allows the CLI repo to be hosted in a directory with spaces. (angular#16073)

child_process.spawn() with `shell: true` does not quote its arguments, so any data passed in must be surrounded by quotes to properly include spaces. This was making tests fail when the repository is checked out to a directory with a space in it.

Easiest solution is to simply not use shell escaping which avoids the whole problem.

Author: dgp1130

packages/angular_devkit/benchmark/src/monitored-process.ts

@@ -37,7 +37,7 @@ export class LocalMonitoredProcess implements MonitoredProcess {
   run(): Observable<number> {
     return new Observable(obs => {
       const { cmd, cwd, args } = this.command;
-      const spawnOptions: SpawnOptions = { cwd: cwd, shell: true };
+      const spawnOptions: SpawnOptions = { cwd };
 
       // Spawn the process.
       const childProcess = spawn(cmd, args, spawnOptions);