builder: avoid duplicate CLI error logging in generated main

[Syedowais312]

Problem

When running an invalid CLI command (for example otelcorecol foo), Cobra already prints a user-facing error message.

However, the builder-generated main.go also logs the same error using log.Fatalf, which results in duplicate error output.

Solution

This change updates the builder template to:

• remove log.Fatalf from main()
• exit with a non-zero status using os.Exit(1)
• allow Cobra to fully own CLI error output

Result

Before

Error: unknown command "foo" for "otelcorecol"
Run 'otelcorecol --help' for usage.
collector server run finished with error: unknown command "foo" for "otelcorecol"

After

Error: unknown command "foo" for "otelcorecol"
Run 'otelcorecol --help' for usage.

Notes

• Change is limited to cmd/builder/internal/builder/templates/main.go.tmpl
• No behavior change for successful execution paths
• Exit code behavior remains unchanged

Closes: #14302

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Syedowais312 / name: syed owais (bd3991a)

[axw]

LGTM, I suggest adding a comment to make it clear that we're intentionally not logging the error though.

[axw]

@Syedowais312 can you please add a changelog entry? It's a small change, but still worthy of an enhancement changelog IMO.

[Syedowais312]

@axw I’ve added a changelog entry and a comment in main.go.tmpl explaining the intentional omission of error logging. let me know if any further changes are needed.

[axw]

@Syedowais312 we shouldn't update this file directly, please see https://github.com/open-telemetry/opentelemetry-collector/blob/main/CONTRIBUTING.md#adding-a-changelog-entry

[Syedowais312]

@axw Thanks for the pointer ,fixed the chloggen entry by removing empty optional fields, validated with make chlog-validate, and updated the PR. Please let me know if anything else is needed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.10%. Comparing base (c216239) to head (bd3991a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #14317   +/-   ##
=======================================
  Coverage   92.10%   92.10%           
=======================================
  Files         668      668           
  Lines       41379    41379           
=======================================
  Hits        38114    38114           
  Misses       2227     2227           
  Partials     1038     1038           

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[axw]

LGTM, thanks @Syedowais312. CI is failing because the generated code in otelcorecol will need changing.