system_server_current is accepted

Previously, has-system-sdk-version incorrectly returned true for
the sdk version 'system_server_current', just because it started with
system_. Since system_server_current is a totally different API surface
than system_*, make the macro to return false for system_server_*.

Bug: 146757305
Test: m
Test: add 'sdk_version: "system_server_current" to wifi-service-pre-jarjar
Change-Id: I43700545b0f120fa987696b8f03a4765d97e13e2