Revert "use getenv_s instead of getenv for Windows. (ros2#499)" (ros2#504) (ros2#506)

This reverts commit 46ab4d4.

(cherry picked from commit 3a4beda)

Co-authored-by: Chris Lalancette <clalancette@gmail.com>

Author: mergify[bot]

src/env.c

@@ -81,27 +81,8 @@ rcutils_get_env(const char * env_name, const char ** env_value)
     return "argument env_value is null";
   }
 
-#ifdef _WIN32
-  size_t requiredSize = 0;
-  char *buffer = NULL;
-  if (getenv_s(&requiredSize, NULL, 0, env_name) == 0 && requiredSize > 0) {
-    buffer = (char *)malloc(requiredSize * sizeof(char));
-    if (buffer != NULL) {
-      if (getenv_s(&requiredSize, buffer, requiredSize, env_name) == 0) {
-        *env_value = buffer;
-      } else {
-        free(buffer);
-        *env_value = NULL;
-      }
-    } else {
-      *env_value = NULL;
-    }
-  } else {
-    *env_value = NULL;
-  }
-#else
+  // TODO(Suyash458): getenv is deprecated on Windows; consider using getenv_s instead
   *env_value = getenv(env_name);
-#endif
 
   if (NULL == *env_value) {
     *env_value = "";