Awake: Corrected label: keep awake on interval -> for duration

[levid0s]

Summary of the Pull Request

Corrected: Keep awake on interval -> Keep awake for duration

"Keep awake on interval" incorrectly suggests that a wake-up event is continuously sent at the selected interval (eg. every 30 minutes).

PR Checklist

• Closes: #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: Updated Awake settings MicrosoftDocs/windows-dev-docs#5093

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[levid0s]

@microsoft-github-policy-service agree

[dend]

We should not do the changes piecemeal - if we're changing terminology, it should be consistently changed across the app, everywhere where interval is used (including variable names and UI components).

Additionally, instead of for duration we should use for specified duration or for custom duration to avoid awkward phrasing.