quickstart/{node, python}/metrics: Add tags for "status" and "error"

[hvent90]

Addresses #470

Part 2 of 2 pull request to reduce cognitive load as reviewing quickstarts is no simple task.

This PR does the following for the Node Metrics quickstart:

1. Removes the "error" measure
2. Creates a tag for "status" and "Error"
3. Sets "status" tag to "OK"
4. Added exception handling
5. If error, "status" tag is set to "ERROR" and "error" tag is set to the error string

This PR does the following for the Python Metrics quickstart:

1. Removes the "error" measure
2. Creates a tag for "status" and "Error"
3. Sets "status" tag to "OK"

[odeke-em]

LGTM, thank you @hvent90!