Revert "[Linux][A11y] implement AtkEditableText interface (#33955)"

This reverts commit 5ca80bd.

Author: zanderso

ci/licenses_golden/licenses_flutter

@@ -2133,9 +2133,6 @@ FILE: ../../../flutter/shell/platform/linux/fl_accessibility_plugin.h
 FILE: ../../../flutter/shell/platform/linux/fl_accessible_node.cc
 FILE: ../../../flutter/shell/platform/linux/fl_accessible_node.h
 FILE: ../../../flutter/shell/platform/linux/fl_accessible_node_test.cc
-FILE: ../../../flutter/shell/platform/linux/fl_accessible_text_field.cc
-FILE: ../../../flutter/shell/platform/linux/fl_accessible_text_field.h
-FILE: ../../../flutter/shell/platform/linux/fl_accessible_text_field_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_backing_store_provider.cc
 FILE: ../../../flutter/shell/platform/linux/fl_backing_store_provider.h
 FILE: ../../../flutter/shell/platform/linux/fl_basic_message_channel.cc

shell/platform/linux/BUILD.gn

@@ -99,7 +99,6 @@ source_set("flutter_linux_sources") {
   sources = [
     "fl_accessibility_plugin.cc",
     "fl_accessible_node.cc",
-    "fl_accessible_text_field.cc",
     "fl_backing_store_provider.cc",
     "fl_basic_message_channel.cc",
     "fl_binary_codec.cc",
@@ -193,7 +192,6 @@ executable("flutter_linux_unittests") {
 
   sources = [
     "fl_accessible_node_test.cc",
-    "fl_accessible_text_field_test.cc",
     "fl_basic_message_channel_test.cc",
     "fl_binary_codec_test.cc",
     "fl_binary_messenger_test.cc",