Refactor fail points which use namespace in its data.

• Make all fail points to use same field name for namespace. Today, they are using different names, such as "ns", "nss", "namespace", etc.
• Create a helper function to match namespace for fail point. For example,  
  /** * Requires the data and `target` referent have lifetimes * that enclose the lifetime of the returned predicate. */inline auto makeFailPointPredicate(const NamespaceString& target) { return [&target](const BSONObj& data) { auto nss = NamespaceStringUti::parseFailPointData(data, "namespace"); return nss.isEmpty() || nss == target; }

  ;
  }