server : replace behave with pytest (#10416)
* server : replace behave with pytest
* fix test on windows
* misc
* add more tests
* more tests
* styling
* log less, fix embd test
* added all sequential tests
* fix coding style
* fix save slot test
* add parallel completion test
* fix parallel test
* remove feature files
* update test docs
* no cache_prompt for some tests
* add test_cache_vs_nocache_prompt
