replace knowhere with megasearch/knowhere

Former-commit-id: ebc5f2dedbdc9fc7efdeecd8f2457f40829bbb31

.gitmodules

 [submodule "cpp/thirdparty/knowhere"]
 	path = cpp/thirdparty/knowhere
-	url = git@192.168.1.105:xiaojun.lin/knowhere.git
-	branch = develop
+	url = git@192.168.1.105:megasearch/knowhere.git
+	branch = branch-0.4.0

knowhere @ 02550a43

+Subproject commit 02550a43b5146bd7976b8b2b3fc37ca885d1e880