InputDecorator M3 tests migration - Step5 - Helper/Counter/Error (#144932)

## Description

This PR migrates `InputDecorator` helper/counter/error related tests to M3 and adds some missing tests.

It is the fifth step for the M3 test migration for `InputDecorator`.
Step 1: https://github.com/flutter/flutter/pull/142981
Step 2: https://github.com/flutter/flutter/pull/143369
Step 3: https://github.com/flutter/flutter/pull/143520
Step 4: https://github.com/flutter/flutter/pull/144169

## Related Issue

Related to https://github.com/flutter/flutter/issues/139076
fixes https://github.com/flutter/flutter/issues/138213