chore(functions): remove BASE_URL env var (#2106)

This variable no longer makes [as much] sense, given that the _system_ tests and _integration_ tests are no longer similar.

Co-authored-by: F. Hinkelmann <[email protected]>

functions/helloworld/test/sample.integration.http.test.js

@@ -20,7 +20,7 @@ const requestRetry = require('requestretry');
 const uuid = require('uuid');
 
 const PORT = process.env.PORT || 8080;
-const BASE_URL = process.env.BASE_URL || `http://localhost:${PORT}`;
+const BASE_URL = `http://localhost:${PORT}`;
 const cwd = path.join(__dirname, '..');
 
 // [END functions_http_integration_test]