Check support for prerelease qualifiers

[pchila]

For 9.0 release Beats need to be packaged using prerelease qualifiers, like:

• beta
• rc1, rc2

The goal of this issue is to check that the relative packages can be correctly generated using mage package, specifically

• File names contain the prerelease qualifiers
• version command output correctly prints the specified qualifiers
• Unified release pipelines work for versions with prerelease qualifiers
• Release candidate can be re-released as final 9.0 version

Notes:

• These qualifiers will be used in staging, so there should be no overlap with SNAPSHOT DRA flow
• At the time of writing we can create an alpha1 version (for example in agentbeat) using

 VERSION_QUALIFIER="alpha1" mage -d ./x-pack/agentbeat package

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[pchila]

Tested packaging agentbeat with VERSION_QUALIFIER="alpha1" mage -d ./x-pack/agentbeat package and the result is consistent with the expectations:

➜  beats git:(main) ✗ tree -L 1 x-pack/agentbeat/build/distributions
x-pack/agentbeat/build/distributions
├── agentbeat-9.0.0-alpha1-darwin-aarch64.tar.gz
├── agentbeat-9.0.0-alpha1-darwin-aarch64.tar.gz.sha512
├── agentbeat-9.0.0-alpha1-darwin-x86_64.tar.gz
├── agentbeat-9.0.0-alpha1-darwin-x86_64.tar.gz.sha512
├── agentbeat-9.0.0-alpha1-linux-arm64.tar.gz
├── agentbeat-9.0.0-alpha1-linux-arm64.tar.gz.sha512
├── agentbeat-9.0.0-alpha1-linux-x86_64
├── agentbeat-9.0.0-alpha1-linux-x86_64.tar.gz
├── agentbeat-9.0.0-alpha1-linux-x86_64.tar.gz.sha512
├── agentbeat-9.0.0-alpha1-windows-x86_64.zip
└── agentbeat-9.0.0-alpha1-windows-x86_64.zip.sha512

version command outputs the version correctly as well

➜  beats git:(main) ✗ x-pack/agentbeat/build/distributions/agentbeat-9.0.0-alpha1-linux-x86_64/agentbeat filebeat version
filebeat version 9.0.0-alpha1 (amd64), libbeat 9.0.0-alpha1 [f6d5accade0a325df0325830f729295178d3d47c built 2025-01-14 17:50:56 +0000 UTC]
➜  beats git:(main) ✗ x-pack/agentbeat/build/distributions/agentbeat-9.0.0-alpha1-linux-x86_64/agentbeat metricbeat version
metricbeat version 9.0.0-alpha1 (amd64), libbeat 9.0.0-alpha1 [f6d5accade0a325df0325830f729295178d3d47c built 2025-01-14 17:50:56 +0000 UTC]

It is also possible to repackage from the same commit as the alpha1 is set and handled via the env var VERSION_QUALIFIER