Fix: Remove references to `text2text-generation`, `summarization` and `translation` pipeline tasks (#44510)
* fix: clean up docs of summarization and translation pipeline
* remove references of text2text-generation task
* Update docs/source/en/tasks/prompting.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
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Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>