impala-profile-tool should support parsing thrift profiles downloaded from WebUI

In the coordinator WebUI, users can download query profiles in text/json/thrift formats. The thrift profile is the same as one line in the profile log without the timestamp and query id at the beginning.

impala-profile-tool fails to parse such a file. It should retry parsing the whole line as the encoded profile. Current code snipper:

    // Parse out fields from the line.
    istringstream liness(line);
    int64_t timestamp;
    string query_id, encoded_profile;
    liness >> timestamp >> query_id >> encoded_profile;
    if (liness.fail()) {
      cerr << "Error parsing line " << lineno << ": '" << line << "'\n";
      ++errors;
      continue;
    }

https://github.com/apache/impala/blob/f620e5d5c0bbdb0fd97bac31c7b7439cd13c6d08/be/src/util/impala-profile-tool.cc#L109