test: fix test-process-env-tz.js by using RegExp

Not all environment returns 'Central European Summer Time', 'British
Summer Time' and 'Coordinated Universal Time'. E.g. Some environment
like Chinese returns '中欧夏令时间', '英国夏令时间' and '协调世界时'.

PR-URL: #42113
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

test/parallel/test-process-env-tz.js

@@ -31,19 +31,19 @@ if (date.toString().includes('(Central European Time)') ||
   common.skip('tzdata too old');
 }
 
-assert.strictEqual(
-  date.toString().replace('Central European Summer Time', 'CEST'),
-  'Sat Apr 14 2018 14:34:56 GMT+0200 (CEST)');
+assert.match(
+  date.toString(),
+  /^Sat Apr 14 2018 14:34:56 GMT\+0200 \(.+\)$/);
 
 process.env.TZ = 'Europe/London';
-assert.strictEqual(
-  date.toString().replace('British Summer Time', 'BST'),
-  'Sat Apr 14 2018 13:34:56 GMT+0100 (BST)');
+assert.match(
+  date.toString(),
+  /^Sat Apr 14 2018 13:34:56 GMT\+0100 \(.+\)$/);
 
 process.env.TZ = 'Etc/UTC';
-assert.strictEqual(
-  date.toString().replace('Coordinated Universal Time', 'UTC'),
-  'Sat Apr 14 2018 12:34:56 GMT+0000 (UTC)');
+assert.match(
+  date.toString(),
+  /^Sat Apr 14 2018 12:34:56 GMT\+0000 \(.+\)$/);
 
 // Just check that deleting the environment variable doesn't crash the process.
 // We can't really check the result of date.toString() because we don't know