Fix alias for superclass with identical name

[kmichel-aiven]

If an externally imported model is renamed because it has the same name as the current model, the alias was incorrectly suffixed with the original name.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1981 +/- ## ======================================= Coverage ? 98.90% ======================================= Files ? 37 Lines ? 4183 Branches ? 972 ======================================= Hits ? 4137 Misses ? 29 Partials ? 17 ``` | [Flag](https://app.codecov.io/gh/koxudaxi/datamodel-code-generator/pull/1981/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Koudai+Aono) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/koxudaxi/datamodel-code-generator/pull/1981/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Koudai+Aono) | `98.56% <ø> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Koudai+Aono#carryforward-flags-in-the-pull-request-comment) to find out more.

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[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #1981 will not alter performance

_{Comparing kmichel-aiven:kmichel-fix-reference-to-superclass (6446dfa) with main (decc493)}

Summary

✅ 29 untouched benchmarks