[tests] Remove unused fuchsia.sys protocol reference (#41826)

Remove reference to unused fuchsia.sys.Environment protocol in test
Realm setup. Besides being unused,
the reference was not correctly matched by an #include, nor a GN build
dependency.

Bug: fxbug.dev/81285

Author: drwez

shell/platform/fuchsia/flutter/tests/integration/utils/portable_ui_test.cc

@@ -77,7 +77,6 @@ void PortableUITest::SetUpRealmBase() {
   // // Route base system services to flutter and the test UI stack.
   realm_builder_.AddRoute(Route{
       .capabilities = {Protocol{fuchsia::logger::LogSink::Name_},
-                       Protocol{fuchsia::sys::Environment::Name_},
                        Protocol{fuchsia::sysmem::Allocator::Name_},
                        Protocol{fuchsia::tracing::provider::Registry::Name_},
                        Protocol{fuchsia::ui::input::ImeService::Name_},