Shortcut control visual tweaks (#42302)

## Summary of the Pull Request

Small design tweaks, resolving a visual glitch where the bottom border
of wasn't displayed correctly, and looked jagged on higher res displays

Before vs after

<img width="654" height="450" alt="image"
src="https://github.com/user-attachments/assets/68ab3d24-d18b-4fae-9ffa-3548ce440798"
/>


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## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the 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](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed

src/settings-ui/Settings.UI/Strings/en-us/Resources.resw

@@ -5173,7 +5173,7 @@ To record a specific window, enter the hotkey with the Alt key in the opposite m
     <value>Configure shortcut</value>
   </data>
   <data name="ConfigureShortcutText.Text" xml:space="preserve">
-    <value>Configure shortcut</value>
+    <value>Assign shortcut</value>
   </data>
   <data name="QuickAccessTitle.Title" xml:space="preserve">
     <value>Quick access</value>