test: fix arguments order

the actual and expected arguments in assert.strictEqual() calls are in
the wrong order. Any literal value should be the second argument while
the first argument should be the value returned by a function/be the
calculated value.

PR-URL: nodejs#24151
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/parallel/test-fs-readfile-empty.js

@@ -35,12 +35,12 @@ fs.readFile(fn, function(err, data) {
 });
 
 fs.readFile(fn, 'utf8', function(err, data) {
-  assert.strictEqual('', data);
+  assert.strictEqual(data, '');
 });
 
 fs.readFile(fn, { encoding: 'utf8' }, function(err, data) {
-  assert.strictEqual('', data);
+  assert.strictEqual(data, '');
 });
 
 assert.ok(fs.readFileSync(fn));
-assert.strictEqual('', fs.readFileSync(fn, 'utf8'));
+assert.strictEqual(fs.readFileSync(fn, 'utf8'), '');