Enable the 'automatic adjustment of indistinguishable text' setting f…

…or Dev builds (#12444)

## Summary of the Pull Request
Followup from our discussion during team sync, the 'automatic adjustment of indistinguishable text' setting is going to be enabled for dev builds only.

## References
#12160 

## PR Checklist
* [ ] Closes #xxx
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: #xxx
* [ ] Schema updated.
* [x] I work here

## Validation Steps Performed
Setting appears on dev build and the feature works

src/features.xml

@@ -80,5 +80,8 @@
         <name>Feature_AdjustIndistinguishableText</name>
         <description>If enabled, the foreground color will, when necessary, be automatically adjusted to make it more visible.</description>
         <stage>AlwaysDisabled</stage>
+        <alwaysEnabledBrandingTokens>
+            <brandingToken>Dev</brandingToken>
+        </alwaysEnabledBrandingTokens>
     </feature>
 </featureStaging>