SQL Log Messages - FILESTREAM and xp_cmdshell
Really not sure what else aside from PBM might be set up to try so forcibly to disable xp_cmdshell, but it definitely sounds like something set up by IT in some way. I don't think this is really causing any problems, so you could just wait until the rest of your team is available and bring it up to them. If you want to get more information about it, you could set up a server-side trace that captures all calls to sp_configure - this will at least tell you the host name, application name, user name etc. 

declare @rc int, @TraceID int, @maxsize BIGINT = 5;

exec @rc = sp_trace_create @TraceID output, 0, N'C:\myfolder\mytrace', @maxsize, NULL 
if (@rc != 0) goto error

declare @on bit = 1;
exec sp_trace_setevent @TraceID, 42, 1, @on;
exec sp_trace_setevent @TraceID, 42, 6, @on;
exec sp_trace_setevent @TraceID, 42, 7, @on;
exec sp_trace_setevent @TraceID, 42, 8, @on;
exec sp_trace_setevent @TraceID, 42, 10, @on;
exec sp_trace_setevent @TraceID, 42, 11, @on;
exec sp_trace_setevent @TraceID, 42, 14, @on;
exec sp_trace_setevent @TraceID, 42, 34, @on;
exec sp_trace_setevent @TraceID, 42, 41, @on;
exec sp_trace_setevent @TraceID, 42, 64, @on;

exec sp_trace_setfilter @TraceID, 34, 0, 6, N'sp_configure';
exec sp_trace_setstatus @TraceID, 1;
select TraceID=@TraceID;
goto finish

error: 
select ErrorCode=@rc

finish: 
go


Probably more event columns there than necessary, but it's not like you're going to be running this for a long time. You should be able to turn it off as soon as you see another message pop up in the log (because I doubt this is coming from multiple sources).