Revert "Sets focus before sending a11y focus event in Android"

[zanderso]

Reverts #27992

It looks like this change caused a failure in

https://ci.chromium.org/ui/p/flutter/builders/prod/Mac_android%20android_semantics_integration_test/2203/overview

[android_semantics_integration_test] [STDOUT] stdout: [ +856 ms] 00:15 �[32m+1�[0m�[31m -1�[0m: AccessibilityBridge TextField password TextField has correct Android semantics �[1m�[31m[E]�[0m�[0m
[android_semantics_integration_test] [STDOUT] stdout: [        ]   Expected: AndroidSemanticsNode with className: android.widget.EditText with actions: [AndroidSemanticsAction.clearAccessibilityFocus, AndroidSemanticsAction.click, AndroidSemanticsAction.copy, AndroidSemanticsAction.setSelection, AndroidSemanticsAction.setText] with flag isEditable: true with flag isFocusable: true with flag isFocused: true with flag isPassword: true
[android_semantics_integration_test] [STDOUT] stdout: [        ]     Actual: AndroidSemanticsNode:<{flags: {isEditable: true, isEnabled: true, isDismissible: false, isCheckable: false, isChecked: false, isFocused: true, isLongClickable: false, isFocusable: true, isPassword: true}, id: 30, text: null, rect: {height: 144, width: 1080, bottom: 592.0, top: 544.0, left: 0.0, right: 360.0}, actions: [131072, 32768, 2097152, 16, 64], className: android.widget.EditText, liveRegion: 0, contentDescription: null}>
[android_semantics_integration_test] [STDOUT] stdout: [        ]      Which: Expected actions: [AndroidSemanticsAction.clearAccessibilityFocus, AndroidSemanticsAction.click, AndroidSemanticsAction.copy, AndroidSemanticsAction.setSelection, AndroidSemanticsAction.setText]
[android_semantics_integration_test] [STDOUT] stdout: [        ]             Actual actions: [AndroidSemanticsAction.accessibilityFocus, AndroidSemanticsAction.click, AndroidSemanticsAction.copy, AndroidSemanticsAction.setSelection, AndroidSemanticsAction.setText]
[android_semantics_integration_test] [STDOUT] stdout: [        ]             Unexpected: {AndroidSemanticsAction.accessibilityFocus}
[android_semantics_integration_test] [STDOUT] stdout: [        ]             Missing: {AndroidSemanticsAction.clearAccessibilityFocus}

Reverting this to get the Engine roll moving again.