fix: update Deepseek configurations (#1083)

* fix: update Deepseek configurations

* fix: restore the "disable" reasoning effort option

* fix: remove deepseek-chat and deekseek-reasoner tests, or change them to deepseek-v4-flash or deepseek-v4-pro

* fix: normalizeDeepSeekReasoningEffort

* chore: add unit testing for normalizeDeepSeekReasoningEffort