test: change assert message to default

assert.strictEqual message argument removed to replace
with default assert message to show the expected vs
actual values

Refs: nodejs#13296

test/known_issues/test-http-path-contains-unicode.js

@@ -10,10 +10,10 @@ const http = require('http');
 
 const expected = '/café🐶';
 
+//Sanity check for café🐶 is café🐶
 assert.strictEqual(
   expected,
-  '/caf\u{e9}\u{1f436}',
-  'Sanity check that string literal produced the expected string'
+  '/caf\u{e9}\u{1f436}'
 );
 
 const server = http.createServer(common.mustCall(function(req, res) {