fix(lsp_spec): tests depended on previous session

backport #15803

- fix tests which accidentally depended on previous session

test/functional/plugin/lsp_spec.lua

@@ -132,10 +132,6 @@ end
 describe('LSP', function()
   before_each(function()
     clear_notrace()
-  end)
-
-  describe('server_name specified', function()
-    before_each(function()
     -- Run an instance of nvim on the file which contains our "scripts".
     -- Pass TEST_NAME to pick the script.
     local test_name = "basic_init"
@@ -164,6 +160,7 @@ describe('LSP', function()
    -- exec_lua("lsp.stop_all_clients(true)")
   end)
 
+  describe('server_name specified', function()
     it('start_client(), stop_client()', function()
       retry(nil, 4000, function()
         eq(1, exec_lua('return #lsp.get_active_clients()'))