Add error message to AvailableMem

Summary:
test:

```
#include <iostream>
#include "utils/sysinfo/memory.hpp"

#include <sys/resource.h>

int main(void) {
  rlimit lim;
  lim.rlim_cur = 0;
  lim.rlim_max = 0;
  setrlimit(RLIMIT_NOFILE, &lim);
  std::cout << utils::AvailableMem();
  return 0;
}
```

Prints out:
```
E0303 15:08:53.314087 17511] Failed to read amount of available memory from /proc/meminfo
```

Reviewers: mferencevic

Reviewed By: mferencevic

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1269

src/utils/sysinfo/memory.hpp

@@ -2,6 +2,8 @@
 #include <iostream>
 #include <limits>
 
+#include "glog/logging.h"
+
 namespace utils {
 
 /**
@@ -22,6 +24,7 @@ inline auto AvailableMem() {
     }
     meminfo.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
   }
+  LOG(ERROR) << "Failed to read amount of available memory from /proc/meminfo";
   return 0UL;
 }
 }  // namespace utils