MDL-67250 setup: Revert removal of the httpswwwroot setting

It is still used widely in the plugins that would stop working suddenly
without being warned via a debugging message. We must keep it forever as
an alias for the wwwroot.

lib/phpunit/tests/basic_test.php

@@ -52,6 +52,10 @@ class core_phpunit_basic_testcase extends basic_testcase {
      */
     public function test_bootstrap() {
         global $CFG;
+
+        // The httpswwwroot has been deprecated, we keep it as an alias for backwards compatibility with plugins only.
+        $this->assertTrue(isset($CFG->httpswwwroot));
+        $this->assertEquals($CFG->httpswwwroot, $CFG->wwwroot);
         $this->assertEquals($CFG->prefix, $CFG->phpunit_prefix);
     }