[Filebeat] Use existing constant for FIPS distribution

[ycombinator]

Proposed commit message

This PR is a follow up to #45036. In that PR, a new constant was introduced in libbeat, common.FIPSMode to determine if we're running a FIPS-capable distribution of a Beat or not. Turns out there was already such a constant in place, version.FIPSDistribution. So this PR here deletes common.FIPSMode and reuses version.FIPSDistribution instead.

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.next.asciidoc or CHANGELOG-developer.next.asciidoc.

How to test this PR locally

$ go test ./filebeat/input/v2/ -test.run TestLoader_ConfigureFIPS -test.count 1 -test.v
=== RUN   TestLoader_ConfigureFIPS
    loader_test.go:209: FIPS mode = false; err = <nil>
--- PASS: TestLoader_ConfigureFIPS (0.00s)
PASS
ok  	github.com/elastic/beats/v7/filebeat/input/v2	0.006s

In an environment configured for FIPS, i.e. with the Microsoft Go fork installed and with the OpenSSL FIPS provider installed:

$ GOEXPERIMENT=systemcrypto go test -tags requirefips ./filebeat/input/v2/ -test.run TestLoader_ConfigureFIPS -test.count 1 -test.v
=== RUN   TestLoader_ConfigureFIPS
    loader_test.go:209: FIPS mode = true; err = running a FIPS-capable distribution but input [a] is not FIPS capable
--- PASS: TestLoader_ConfigureFIPS (0.00s)
PASS
ok  	github.com/elastic/beats/v7/filebeat/input/v2	0.014s

[github-actions]

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Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[ycombinator]

CI is failing like so:

=== FAIL: x-pack/filebeat/fbreceiver TestReceiverDegraded/failed_input (3.36s)
--
  | SDK 2025/06/26 12:09:08 WARN falling back to IMDSv1: operation error ec2imds: getToken, http response error StatusCode: 405, request to EC2 IMDS failed
  | oteltest.go:187:
  | Error Trace:	/opt/buildkite-agent/builds/bk-agent-prod-gcp-1750939501187081759/elastic/beats-xpack-filebeat/libbeat/otelbeat/oteltest/oteltest.go:187
  | /opt/buildkite-agent/.asdf/installs/golang/1.24.4/go/src/runtime/asm_amd64.s:1700
  | Error:      	Expected value not to be nil.
  | Test:       	TestReceiverDegraded/failed_input
  | Messages:   	expected not nil nil, got <nil>
  | oteltest.go:156: Ingested Logs: map[]
  |  
  | === FAIL: x-pack/filebeat/fbreceiver TestReceiverDegraded (9.65s)

This failure is unrelated to the changes in this PR. It can also be seen on main CI builds, e.g. https://buildkite.com/elastic/beats-xpack-filebeat/builds/17300#0197aba6-a712-480f-b28d-c9931ebe98bf.

@pierrehilbert is it OK to force merge this PR once all other checks are successful? Will wait until the test is skipped via #45058 then rebase this PR on main and run CI on it again.

[VihasMakwana]

@ycombinator the flaky test PR is merged.