rapl_collector: fix issue with invalid metric name (#2299)

[aneagoe]

Fixes #2299 by wrapping metric name in SanitizeMetricName() as suggested by @discordianfish

[alanorth]

Tested on a bare metal AMD EPYC 7451:

# lscpu | grep Model\ name:
Model name:          AMD EPYC 7451 24-Core Processor
BIOS Model name:     AMD EPYC 7451 24-Core Processor

Works! Before this node_exporter was crashing every fifteen seconds when I scraped.

[SuperQ]

Thanks, I think there was another similar PR, or issue filed. There was some discussion about making this a label.

[aneagoe]

@SuperQ my bad, I got the timelines mixed and thought wrapping suggestion came later. I have no preference, but I wouldn't know how to make the label change myself and atm we're a bit in limbo with this (ie no one seems to be working on converting to label). It would be great to merge this and in parallel work on a more proper solution.

[SuperQ]

Yea, it's a breaking change as well. I have a couple ideas, I will see if I can write something up tomorrow to fix it both ways.

For now, I think this is a sane option.