Replace builtin json with faster ujson package.

[purple4reina]

What does this PR do?

Replaces instances of the builtin json package to use ujson instead.

Motivation

The builtin json package is pretty slow for loading/dumping data. There are faster alternatives.

Testing Guidelines

Additional Notes

I evaluated several packages to determine which was best.

package	total mean bench*	package size
json	22269.8497	-
ujson	20729.369	184K
msgspec	22589.6351	604K
orjson	21399.4234	628K
rapidjson	20626.785	916K
simplejson	22365.0746	288K

* "total mean bench" is the sum of all the mean durations of all benchmarks.

Some packages were faster/slower depending on the lambda event payload. But I ultimately went with ujson because it is generally one of the fastest, plus has smallest package size.

Some benchmark results

Comparison of json and ujson when extracting trace context from an sqs batch event.

Curling lambda url with capture lambda payload true.

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)

[astuyve]

Needs to be added to the LICENSE-3rdparty.csv file, otherwise it's good