[EEP-444] include error in failed metric send log

[CoreyGriffin]

What does this PR do?

• Includes the error when statsd client fails to send the metric

Motivation

• Ran into an issue where metrics were sporadically failing to send when using the serverless plugin. Needed the know error to resolve underlying issue.

Testing Guidelines

• Tested in lambda functions that were originally failing to send metrics and was able to identify and resolve the issue.

Example

{
    "status": "error",
    "message": "datadog: could not send metric <metric name>"
}

Original output

{
    "status": "error",
    "message": "datadog: could not send metric <metric name>: statsd buffer is full"
}

New output

Additional Notes

• None

Types of changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Checklist

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog

[codecov-commenter]

Codecov Report

Merging #118 (c217e21) into main (bf8b37f) will decrease coverage by 1.30%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #118      +/-   ##
==========================================
- Coverage   84.51%   83.21%   -1.31%     
==========================================
  Files          13       13              
  Lines         788      846      +58     
==========================================
+ Hits          666      704      +38     
- Misses         96      113      +17     
- Partials       26       29       +3     

Impacted Files	Coverage Δ
internal/metrics/listener.go	83.06% <0.00%> (ø)
internal/extension/extension.go	80.26% <0.00%> (-10.65%)	⬇️
internal/trace/listener.go	54.92% <0.00%> (-3.14%)	⬇️
internal/metrics/processor.go	97.70% <0.00%> (-2.30%)	⬇️
internal/wrapper/wrap_handler.go	97.93% <0.00%> (+0.02%)	⬆️
ddlambda.go	79.61% <0.00%> (+1.04%)	⬆️

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