refactor(dev-infra): use the exec() helper from utils/shelljs whenever possible (#37444)

There is an `exec()` helper provided by `utils/shelljs.ts`, which is a
wrapper around ShellJS' `exec()` with some default options (currently
`silent: true`). The intention is to avoid having to pass these options
to every invocation of the `exec()` function.

This commit updates all code inside `dev-infra/` to use this helper
whenever possible).

NOTE: For simplicity, the `utils/shelljs` helper does not support some
      of the less common call signatures of the original `exec()`
      helper, so in some cases we still need to use the original.

PR Close #37444

dev-infra/commit-message/validate-range.ts

@@ -5,9 +5,8 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-import {exec} from 'shelljs';
-
 import {info} from '../utils/console';
+import {exec} from '../utils/shelljs';
 
 import {parseCommitMessage, validateCommitMessage, ValidateCommitMessageOptions} from './validate';
 
@@ -26,7 +25,7 @@ export function validateCommitRange(range: string) {
   const gitLogFormat = `%s%n%n%b${randomValueSeparator}`;
 
   // Retrieve the commits in the provided range.
-  const result = exec(`git log --reverse --format=${gitLogFormat} ${range}`, {silent: true});
+  const result = exec(`git log --reverse --format=${gitLogFormat} ${range}`);
   if (result.code) {
     throw new Error(`Failed to get all commits in the range: \n  ${result.stderr}`);
   }