## Description
This PR replaces global `ThemeData.inputDecorationTheme` usage in
`TextFormField` with `InputDecorationTheme.of ` which returns the
ambient `InputDecorationTheme`.
It is a follow up to https://github.com/flutter/flutter/pull/168981
which introduces `InputDecorationTheme.of `.
## Related Issue
Fixes [TextFormField does not inherit local
InputDecorationTheme](https://github.com/flutter/flutter/issues/176391)
## Tests
- Adds 1 test
067d793084