Bug#35630329 reading master key fails if keyring-path contains symlink

Post-push fix:
Adjusting the existing test MasterKeyFileNotChangedAfterSecondBootstrap
to the changes to make it pass on MacOs.

Change-Id: If3af931d86978d8087100274bf631adbbe420cc1

Author: Andrzej Religa

router/tests/component/test_bootstrap.cc

@@ -1626,14 +1626,14 @@ TEST_F(RouterBootstrapTest,
  *       verify that master key file is not overridden by subsequent bootstrap.
  */
 TEST_F(RouterBootstrapTest, MasterKeyFileNotChangedAfterSecondBootstrap) {
-  std::string master_key_path =
-      Path(bootstrap_dir.name()).join("mysqlrouter.key").str();
-  std::string keyring_path =
-      Path(bootstrap_dir.name()).join("data").join("keyring").str();
-
   mysql_harness::mkdir(Path(bootstrap_dir.name()).str(), 0777);
   mysql_harness::mkdir(Path(bootstrap_dir.name()).join("data").str(), 0777);
 
+  const std::string master_key_path =
+      Path(bootstrap_dir.name()).real_path().join("mysqlrouter.key").str();
+  const std::string keyring_path =
+      Path(bootstrap_dir.name()).real_path().join("data").join("keyring").str();
+
   SCOPED_TRACE("// create the keyrings manually.");
   auto &proc = launch_command(get_origin().join("mysqlrouter_keyring").str(),
                               {