lacros: not to import system_page_browser_proxy.js.

crrev.com/c/2616981 started to exclude system page from Lacros,
but there seems a missing check in the CL. This CL is its follow up.

Bug: 1166000
Test: Built locally.
Change-Id: Ic3d6b4b49f2a3673abf6efe6202716e7c8592631
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2626850
Auto-Submit: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842958}

chrome/browser/resources/settings/lazy_load.js

@@ -94,7 +94,7 @@ export {kControlledByLookup} from './site_settings/site_settings_behavior.js';
 export {ContentSettingProvider, DefaultContentSetting, RawChooserException, RawSiteException, RecentSitePermissions, SiteException, SiteGroup, SiteSettingsPrefsBrowserProxy, SiteSettingsPrefsBrowserProxyImpl, ZoomLevelEntry} from './site_settings/site_settings_prefs_browser_proxy.js';
 export {WebsiteUsageBrowserProxyImpl} from './site_settings/website_usage_browser_proxy.js';
 export {defaultSettingLabel} from './site_settings_page/site_settings_list.js';
-// <if expr="not chromeos">
+// <if expr="not chromeos and not lacros">
 export {SystemPageBrowserProxyImpl} from './system_page/system_page_browser_proxy.js';
 
 // </if>