Remove unused await code

[drown0315]

Remove some unused await code

before:

  Future<int> _stopDaemon() async {
    if (Platform.isWindows) {
      return await exec('.\\third_party\\gradlew.bat', ['--stop']);
    } else {
      return await exec('./third_party/gradlew', ['--stop']);
    }
  }

after:

  Future<int> _stopDaemon() {
    if (Platform.isWindows) {
      return exec('.\\third_party\\gradlew.bat', ['--stop']);
    } else {
      return exec('./third_party/gradlew', ['--stop']);
    }
  }

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read the Flutter Style Guide recently, and have followed its advice.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[jwren]

Thank you for the PR!

[goderbauer]

(triage) @drown0315 github is complaining that your commit is not signed and that's why merging it is blocked. Could you take a look and fix that? See also https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification

[drown0315]

Thank for reply, I'll take care of that later.

[drown0315]

(triage) @drown0315 github is complaining that your commit is not signed and that's why merging it is blocked. Could you take a look and fix that? See also https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification

It's ok!

[chunhtai]

(triage) looks like there is some conflict. Hi @drown0315, can you resolve the merge conflict?