[Permissions][CTS] Fix MediaPermissionTest for Wear

Update the buttom for Wear since it should be recognize through content
description instead of view id.

Bug: 301145745
Test: atest CtsPermissionUiTestCases:
android.permissionui.cts.MediaPermissionTest#testWhenVisualIsDeniedManuallyThenShouldDenyAllPermissions
android.permissionui.cts.MediaPermissionTest#testWhenAuralIsGrantedManuallyThenShouldGrantAllPermissions
android.permissionui.cts.MediaPermissionTest#testWhenRESIsGrantedManuallyThenShouldGrantAllPermissions
android.permissionui.cts.MediaPermissionTest#testWhenVisualIsGrantedManuallyThenShouldGrantAllPermissions
android.permissionui.cts.MediaPermissionTest#testWhenRESIsDeniedManuallyThenShouldDenyAllPermissions
android.permissionui.cts.MediaPermissionTest#testWhenAuralIsDeniedManuallyThenShouldDenyAllPermissions
android.permissionui.cts.MediaPermissionTest#testWhenRESIsDeniedFromGrantDialogThenShouldDenyAllPermissions

Change-Id: I6a81da82f3db131a264d90f610c9be6ebaa49824