chore!: regenerate from LD OpenAPI spec 18.0.0 [EXPT-3347]

[bvivio]

Ran make openapi-spec-update to regenerate the code using the most recent LaunchDarkly OpenAPI spec, which is 18.0.0.

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

Provide links to any issues in this repository or elsewhere relating to this pull request.

Describe the solution you've provided

Provide a clear and concise description of what you expect to happen.

Describe alternatives you've considered

Provide a clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context about the pull request here.

---

Related Jira issue: EXPT-3347: Regenerate client libraries and LD CLI for new major version release

[bvivio]

Confirmed after building the ldcli locally that the experiments resource no longer lists the get-results command/endpoint, which has been removed in the 18.0.0 OpenAPI spec:

% make
go build -o ldcli

% ./ldcli experiments --help
...
Usage:
  ldcli experiments [command]

Available Commands:
  create           Create experiment
  create-iteration Create iteration
  get              Get experiment
  get-settings     Get experimentation settings
  list             Get experiments
  replace-settings Update experimentation settings
  update           Patch experiment

Global flags:
  -h, --help                  Get help about any command
      --access-token string   LaunchDarkly access token with write-level access
      --analytics-opt-out     Opt out of analytics tracking
      --base-uri string       LaunchDarkly base URI (default "https://app.launchdarkly.com")
  -o, --output string         Command response output format in either JSON or plain text (default "plaintext")