Merge pbench-collect-sysinfo and pbench-metadata-log into pbench-tool-meister-start

[portante]

We should consider merging pbench-collect-sysinfo and pbench-metadata-log into the pbench-tool-meister-start|stop calls.

We could move the default set of sysinfo collections performed into the pbench-agent.cfg file, and then when pbench-tool-meister-start begins, it could load those values from the global configuration. The command line options for --sysinfo could be passed as an argument to pbench-tool-meister-start and then submitted with the base Tool Meister information posted in Redis for each instance.

Then pbench-tool-meister-start could initiate the client message instead of having each benchmark handle this flow. This seems appealing to do in this commit. Let me first get end-to-end collection of the system information first, and then I'll see about collapsing as described.

The pbench-metadata-log is mostly about collecting data about the tools and where they are run. Since pbench-tool-meister-start handles all that today, we should have that code write out the metadata.log contents.

Originally posted by @portante in #1981 (comment)