Refactor(search): merge the legacy folder into Search service folder (#39291)

* Merge the legacy folder into Search service folder

* Move api version 2015-02-28, 2016-09-01, 2017-11-11 from preview to stable

* Fix go sdk ci error

* fix go ci failuer

* Remove Go config

* Revert client.tsp

* Add legacy api version references

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Co-authored-by: ZiWei Chen <98569699+kazrael2119@users.noreply.github.com>
Co-authored-by: Qiaoqiao Zhang <55688292+qiaozha@users.noreply.github.com>
Co-authored-by: Judy Liu <v-liujudy@microsoft.com>
Co-authored-by: Chenjie Shi <tadelesh.shi@live.cn>

Author: 5 people