feat: Clean build and copy handler.js

[astuyve]

What does this PR do?

Removes a local dist directory if it exists, and then copies the cjs handler to be just a regular handler.js, which was removed in 6.76 (but phantom-published until 6.82, as yarn doesn't perform clean builds)

closes #305

Motivation

Testing Guidelines

Additional Notes

Types of Changes

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

Check all that apply

• 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
• This PR passes the integration tests (ask a Datadog member to run the tests)

[codecov-commenter]

Codecov Report

Merging #307 (44f50f3) into main (5d7862c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #307   +/-   ##
=======================================
  Coverage   80.05%   80.05%           
=======================================
  Files          36       36           
  Lines        1715     1715           
  Branches      387      387           
=======================================
  Hits         1373     1373           
  Misses        290      290           
  Partials       52       52           

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