Modifying ps_trace_statement_digest and ps_trace_thread

A couple of the changes we discussed yesterday.

Modifying ps_trace_statement_digest and ps_trace_thread so:

   * sql_log_bin is set to OFF already in the topmost procedures
   * restore INSTRUMENTED for the thread executing the procedure

and fix that in_auto_enable didn't actually do anything for ps_trace_statement_digest.sql