Remove built-in e2e test templates

These never really worked due to some vscode issue; plus, we have our own tests in analysis/ already.

Though it's a good idea to explore these tests, so we should put them back one day. See the proper way to do it: https://github.com/microsoft/vscode-languageserver-node/blob/faa68d90a976f158a8403a0f5cce54117ce61dbb/client-node-tests/bin/runTests.js

Author: chenglou

.gitignore

@@ -2,5 +2,4 @@
 out
 node_modules
 client/server
-.vscode-test
 *.exe