Remove NuGet.config configurations (#1835)

NuGet.config

@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<configuration>
-  <packageSources>
-    <clear />
-    <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
-    <!--
-    <add key="Esprima" value="https://www.myget.org/F/esprimadotnet/api/v3/index.json" />
-    -->
-  </packageSources>
-  <disabledPackageSources />
-</configuration>

NuGet.release.config

@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<configuration>
-  <packageSources>
-    <clear />
-    <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
-  </packageSources>
-  <disabledPackageSources />
-</configuration>