fix(checkbox): tickmark not rendered correctly in indigo theme

[simeonoff]

Closes #15021

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them

[simeonoff]

@desig9stein Please, also validate all themes look and work correctly, not just indigo.

[dobromirts]

The issue persists with that fix. Should we consider using a similar approach from input-group.component? I tested it, and it seems to work well in my opinion.
and the result is as expected in AB -

[simeonoff]

@dobromirts Interesting, it works in the dev demos, perhaps something else is triggering change detection there. Will update it as you suggest and push soon.

[simeonoff]

@dobromirts Can you validate the implementation again?

[dobromirts]

@dobromirts Can you validate the implementation again?

@simeonoff Thank you! Everything is working perfectly.