Fix isolate_tests for app_list_presenter_unittests

After https://codereview.chromium.org/1934213002/ enable_app_list
is on longer set on Linux, and the condition for building
app_list_presenter_unittests is now only "use_aura==1". Update
gn_migration.gypi accordingly to make app_list_presenter_unittests_run
part of "all" when app_list_presenter_unittests is.

BUG=600915
R=dpranke@chromium.org

Review URL: https://codereview.chromium.org/2003703002 .

Cr-Commit-Position: refs/heads/master@{#395144}

build/gn_migration.gypi

@@ -665,7 +665,7 @@
                 '../ui/app_list/app_list.gyp:app_list_unittests_run',
               ],
             }],
-            ['enable_app_list==1 and use_aura==1', {
+            ['use_aura==1', {
               'dependencies': [
                 '../ui/app_list/presenter/app_list_presenter.gyp:app_list_presenter_unittests_run',
               ],