[CI] Add retry to test serverless pipeline

[mrodm]

Sometimes CI pipeline in charge of testing elastic-package with Serverless fails when creating the Serverless project:

Error: booting up the stack failed: failed to create deployment: failed to get fleet URL: failed to query fleet server hosts: could not find a fleet server URL

Example build: https://buildkite.com/elastic/elastic-package-test-serverless/builds/548#01993725-bd96-4312-aca7-f7bc1d972eaa/441-469

This PR adds automatic retries in the Buildkite pipeline just if the error happens when creating the Serverless project when running elastic-package stack up command.

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/549

[mrodm]

It cannot be used Buildkite retry approach, since .buildkite/hooks/pre-exit sets another exit coed.

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/550

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/551

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/552

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/553

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: bc7b89b

History

• 💚 Build #6086 succeeded 2d780a8
• 💚 Build #6079 succeeded 632cf88

cc @mrodm

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/554

[mrodm]

test serverless

[elastic-vault-github-plugin-prod]

Triggered serverless pipeline: https://buildkite.com/elastic/elastic-package-test-serverless/builds/555

[mrodm]

Closing in favor of #2901