Revert "Read the provider from the settings, not the migration PROVIDER_FILE"

This reverts commit 001749564d.

PROVIDER is still very much alive and active. sysinfo provider is for the network
interface

src/settings.js

@@ -664,13 +664,15 @@ function initCache(callback) {
     getAll(function (error, allSettings) {
         if (error) return callback(error);
 
+        const provider = safe.fs.readFileSync(paths.PROVIDER_FILE, 'utf8');
+
         gCache = {
             apiServerOrigin: allSettings[exports.API_SERVER_ORIGIN_KEY],
             webServerOrigin: allSettings[exports.WEB_SERVER_ORIGIN_KEY],
             adminDomain: allSettings[exports.ADMIN_DOMAIN_KEY],
             adminFqdn: allSettings[exports.ADMIN_FQDN_KEY],
             isDemo: allSettings[exports.DEMO_KEY],
-            provider: allSettings[exports.SYSINFO_CONFIG_KEY].provider
+            provider: provider ? provider.trim() : 'generic'
         };
 
         callback();