Revert "Support block delete with word and line modifiers (#77172)" - #79674

00:42 +1356 ~13 -1: /opt/s/w/ir/k/flutter/packages/flutter/test/rendering/editable_test.dart: arrow keys and delete handle surrogate pairs correctly case 2 [E]                                        
  Expected: ''
    Actual: '👍'
     Which: is different. Both strings start the same, but the actual value also has the following trailing characters: 👍
  
  package:test_api                                   expect
  package:flutter_test/src/widget_tester.dart 441:3  expect
  test/rendering/editable_test.dart 1116:5           main.<fn>