#[52258045] Updating the valid metric regex to disallow ip addresses and...

... only allow integers and floats

Sidekick: @rantler 
Review: @leeatchison 
FYI: @kevin-mcguire 

The original regex pattern for valid metric values was too permissive and allowed values such as an ip address to be considered a valid metric. Updated the regex to be more restrictive and only allow for integers and floats. See unit tests for valid and invalid cases.