test: s/assert.equal/assert.strictEqual/

Use assert.strictEqual instead of assert.equal in tests, manually
convert types where necessary.

PR-URL: https://github.com/nodejs/node/pull/10698
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>

test/parallel/test-https-set-timeout-server.js

@@ -117,7 +117,7 @@ test(function serverRequestNotTimeoutAfterEnd(cb) {
 test(function serverResponseTimeoutWithPipeline(cb) {
   let caughtTimeout = '';
   process.on('exit', function() {
-    assert.equal(caughtTimeout, '/2');
+    assert.strictEqual(caughtTimeout, '/2');
   });
   const server = https.createServer(serverOptions, function(req, res) {
     res.setTimeout(50, function() {