Fix two more flaky tests (#11095)

* mode_spec: retry with increasing matchtime

`matchtime=2` might still be too low (with luacov on AppVeyor).

    [  ERROR   ] test/functional\ui\mode_spec.lua @ 47: ui mode_change event works in insert mode
    test\functional\ui\screen.lua:587: mode
    Expected objects to be the same.
    Passed in:
    (string) 'insert'
    Expected:
    (string) 'showmatch'
    Hint: full state of "mode":
      "insert"

Followup to fe60013fb.
ref #10941
Initially regressed in 7ed2122622

``

* ui/screen_basic_spec: set timeoutlen=10000

This fixes the test on slow CI.

Ref: https://ci.appveyor.com/project/neovim/neovim/builds/27600387/job/t468h2b3w9lwtlm5#L10930

test/functional/ui/mode_spec.lua

@@ -3,6 +3,7 @@ local Screen = require('test.functional.ui.screen')
 
 local clear, feed, insert = helpers.clear, helpers.feed, helpers.insert
 local command = helpers.command
+local retry = helpers.retry
 
 describe('ui mode_change event', function()
   local screen
@@ -61,30 +62,36 @@ describe('ui mode_change event', function()
                                |
     ]], mode="normal"}
 
+    local matchtime = 0
     command("set showmatch")
-    command("set matchtime=2") -- tenths of seconds
-    feed('a(stuff')
-    screen:expect{grid=[[
-      word(stuff^               |
-      {0:~                        }|
-      {0:~                        }|
-      {2:-- INSERT --}             |
-    ]], mode="insert"}
+    retry(nil, nil, function()
+      matchtime = matchtime + 1
+      local screen_timeout = 1000 * matchtime  -- fail faster for retry.
 
-    feed(')')
-    screen:expect{grid=[[
-      word^(stuff)              |
-      {0:~                        }|
-      {0:~                        }|
-      {2:-- INSERT --}             |
-    ]], mode="showmatch"}
+      command("set matchtime=" .. matchtime) -- tenths of seconds
+      feed('a(stuff')
+      screen:expect{grid=[[
+        word(stuff^               |
+        {0:~                        }|
+        {0:~                        }|
+        {2:-- INSERT --}             |
+      ]], mode="insert", timeout=screen_timeout}
 
-    screen:expect{grid=[[
-      word(stuff)^              |
-      {0:~                        }|
-      {0:~                        }|
-      {2:-- INSERT --}             |
-    ]], mode="insert"}
+      feed(')')
+      screen:expect{grid=[[
+        word^(stuff)              |
+        {0:~                        }|
+        {0:~                        }|
+        {2:-- INSERT --}             |
+      ]], mode="showmatch", timeout=screen_timeout}
+
+      screen:expect{grid=[[
+        word(stuff)^              |
+        {0:~                        }|
+        {0:~                        }|
+        {2:-- INSERT --}             |
+      ]], mode="insert", timeout=screen_timeout}
+    end)
   end)
 
   it('works in replace mode', function()

test/functional/ui/screen_basic_spec.lua

@@ -915,6 +915,7 @@ local function screen_tests(linegrid)
 
   -- Regression test for #8357
   it('does not have artifacts after temporary chars in insert mode', function()
+    command('set timeoutlen=10000')
     command('inoremap jk <esc>')
     feed('ifooj')
     screen:expect([[