Update Vagrantfile dev box

[AndersonQ]

• Use latest Ubuntu LTS
• Change the name to elastic-agent

What does this PR do?

Updates the vagrant dev box

Why is it important?

The current box uses a old ubuntu image and its name is a way too generic

Checklist

• [ ] My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added an entry in ./changelog/fragments using the [changelog tool](https://github.com/elastic/elastic-agent#changelog)~~
• [ ] I have added an integration test or an E2E test

How to test this PR locally

Run
vagrant up elastic-agent

a Vagrant box using virtualbox should start successfully

Use cases

General Elastic Agent development

Questions to ask yourself

• How are we going to support this in production? N/A
• How are we going to measure its adoption? N/A
• How are we going to debug this? N/A
• What are the metrics I should take care of? N/A

[elasticmachine]

💚 Build Succeeded

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• Start Time: 2023-04-05T05:05:03.625+0000

• Duration: 19 min 34 sec

Test stats 🧪

Test	Results
Failed	0
Passed	5387
Skipped	23
Total	5410

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

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To re-run your PR in the CI, just comment with:

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[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	98.485% (65/66)	👍
Files	69.604% (158/227)	👍
Classes	68.736% (299/435)	👍
Methods	53.915% (909/1686)	👍
Lines	39.061% (10178/26057)	👍 0.035
Conditionals	100.0% (0/0)	💚

[pierrehilbert]

Are we sure no one is using dev?
Maybe change to have both dev and elastic-agent working would be better?

[AndersonQ]

Are we sure no one is using dev? Maybe change to have both dev and elastic-agent working would be better?

The problem with dev is that if another box has got the same name they will conflict.
Someone might be using dev, but then they can just recreate the box, or edit the vagrant file and keep the change local.

From a perspective of a "the recommended way to use vagrant for agent development", using only elastic-agent as the name is better.