fix(go-server): use operationId consistently to fix uncompilable output for duplicate operationIds

[halfcrazy]

When two paths share the same auto-generated operationId (e.g. /foo and /foo/), go-server and go-gin-server produced uncompilable code: the route map and interfaces used {{operationId}} (deduplicated to FooGet_0 by addOperationToGroup) while the controller handler and service stub used {{nickname}} (deduplicated to FooGet_1 by a separate pass with a different counter convention), so routes referenced handlers that didn't exist.

Switch the go-server/go-gin-server templates from {{nickname}} to {{operationId}} so routes, interfaces, handlers and service stubs all reference the same deduplicated name. This is a no-op for non-duplicate operationIds and leaves DefaultGenerator untouched, so no other generator is affected.

Add regression tests for both generators covering the /foo + /foo/ case.

fix #24167

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@kemokemo

[cubic-dev-ai]

No issues found across 8 files

_{Re-trigger cubic}

[wing328]

thanks for the PR

cc @antihax (2017/11) @grokify (2018/07) @kemokemo (2018/09) @jirikuncar (2021/01) @ph4r5h4d (2021/04) @lwj5 (2023/04)

[wing328]

lgtm. thanks for the fix