[8.16](backport #6273) Log warning on same version upgrade to prevent failed status

[mergify]

What does this PR do?

Log warning on same version upgrade and filter error to prevent upgrade status reporting.
If a user attempts to upgrade to the same version, the elastic-agent upgrade call will exit with an error, but the agent's status will be cleared of any upgrade markers.

Include an earlier check for same-version upgrades before artifacts are downloaded to prevent unnecessary downloads

Why is it important?

Currently upgrading to the same version results in the agent reporting a failed state until a successful upgrade can be done.

Testing instructions

Install a stand-alone agent and use elastic-agent upgrade 9.0.0-SNAPSHOT --source-uri file://path/to/dir --skip-verification to upgrade the agent

For example:

# Install the agent
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ sudo ./elastic-agent install --develop
Installing into development namespace; this is an experimental and currently unsupported feature.
Elastic Agent will be installed at /Library/Elastic/Agent-Development and will run as a service. Do you want to continue? [Y/n]:y
Do you want to enroll this Agent into Fleet? [Y/n]:n
[   =] Service Started  [4s] Elastic Agent successfully installed, starting enrollment.
[   =] Done  [4s]
Elastic Agent has been successfully installed.

# Check status and version
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ sudo elastic-development-agent version
Binary: 9.0.0-SNAPSHOT (build: 14e78753e6c06295e3348a00de01ae54905fb2c0 at 2024-12-18 18:30:32 +0000 UTC)
Daemon: 9.0.0-SNAPSHOT (build: 14e78753e6c06295e3348a00de01ae54905fb2c0 at 2024-12-18 18:30:32 +0000 UTC)
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ sudo elastic-development-agent status
┌─ fleet
│  └─ status: (STOPPED) Not enrolled into Fleet
└─ elastic-agent
   └─ status: (HEALTHY) Running

# attempt to upgrade to the same version
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ sudo elastic-development-agent upgrade 9.0.0-SNAPSHOT --source-uri file:///Users/mlaterman/git/elastic-agent/build/distributions/ --skip-verify
Upgrade triggered to version 9.0.0-SNAPSHOT, Elastic Agent is currently restarting
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ echo $?
0
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ sudo elastic-development-agent status
┌─ fleet
│  └─ status: (STOPPED) Not enrolled into Fleet
└─ elastic-agent
   └─ status: (HEALTHY) Running
elastic-agent-9.0.0-SNAPSHOT-darwin-aarch64|⇒ sudo elastic-development-agent version
Binary: 9.0.0-SNAPSHOT (build: 14e78753e6c06295e3348a00de01ae54905fb2c0 at 2024-12-18 18:30:32 +0000 UTC)
Daemon: 9.0.0-SNAPSHOT (build: 14e78753e6c06295e3348a00de01ae54905fb2c0 at 2024-12-18 18:30:32 +0000 UTC)

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
• I have added an integration test or an E2E test

Disruptive User Impact

N/A

Related issues

• Closes 8.13.0+ Fleet managed agents upgraded to the currently running version report failed upgrades until a successful upgrade occurs #6186

  ---

  This is an automatic backport of pull request Log warning on same version upgrade to prevent failed status #6273 done by Mergify.

[michel-laterman]

buildkite test this

[mergify]

This pull request has not been merged yet. Could you please review and merge it @michel-laterman? 🙏

[michel-laterman]

It looks like it fails on windows systems.
I've added a little more details to the error message to see if I can find an issue:

>>> (windows-amd64-2022-upgrade) Test output (sudo) (stdout): fixture.go:663: >> running binary with: [C:\Program Files\Elastic\Agent\elastic-agent.exe status --output json]
>>> (windows-amd64-2022-upgrade) Test output (sudo) (stdout): upgrader.go:527: version mismatch, ignoring it, time until timeout: 9.9224238s
>>> (windows-amd64-2022-upgrade) Test output (sudo) (stdout): fixture.go:663: >> running binary with: [C:\Program Files\Elastic\Agent\elastic-agent.exe status --output json]
>>> (windows-amd64-2022-upgrade) Test output (sudo) (stdout): upgrader.go:534: waiting for healthy agent and proper version: could not unmarshal agent status output, body: "": unexpected end of JSON input

However If I run the same command on the system I get:

windows@OGC-WINDOWS-AMD C:\Users\windows> "C:\Program Files\Elastic\Agent\elastic-agent.exe" status --output json
{
    "info": {
        "id": "37dc4d20-3319-4b29-bc6e-e71c4e6e4c35",
        "version": "8.16.3",
        "commit": "db4189af1d36d5bfe5904719f9357a72481c700f",
        "build_time": "2025-01-07 00:28:31 +0000 UTC",
        "snapshot": true,
        "pid": 2280,
        "unprivileged": true
    },
    "state": 2,
    "message": "Running",
    "components": [],
    "FleetState": 6,
    "FleetMessage": "Not enrolled into Fleet"
}

[mergify]

This pull request has not been merged yet. Could you please review and merge it @michel-laterman? 🙏

[elastic-sonarqube]

Quality Gate passed

Issues
1 New issue
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
42.3% Coverage on New Code
0.0% Duplication on New Code

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