Use consistent naming for the extension in the repository and across communications

[jlvoiseux]

The full name of the extension is Elastic APM AWS Lambda extension (as clarified by the following review). While this name is already generally used across the documentation, there are still a few misnaming occurrences in the docs or in the first dedicated blog post.

[simitt]

@bmorelli25 do you have time to pick this up or should we try to schedule on our end?

[bmorelli25]

Tasks:

• Fix blog post | Changes are live
• Add shared attribute in elastic/docs | Add APM AWS Lambda extension attr docs#2471
• Fix Monitoring AWS guide docs | docs: consistent naming #226
• Fix Node.js agent docs | docs: consistent naming of APM AWS Lambda extension apm-agent-nodejs#2815
• Fix Python agent docs | docs: consistent naming of APM AWS Lambda extension apm-agent-python#1582
• Fix Java agent docs | docs: consistent naming of APM AWS Lambda extension apm-agent-java#2704