Backport #21597
Related:
* https://github.com/go-gitea/gitea/pull/21596#issuecomment-1291450224
There was a bug when switching language by AJAX: the irrelevant POST
requests were processed by the target page's handler.
Now, use GET instead of POST. The GET requests should be harmless.
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>