patch 9.1.1104: CI: using Ubuntu 22.04 Github runners

Problem:  CI: uses Ubuntu 22.04 runners
Solution: Switch to Ubuntu 24.04 runners, make a few adjustments for
          different $TMPDIR (Drew Vogel)

closes: #16442

Signed-off-by: Drew Vogel <dvogel@github>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_messages.vim b/src/testdir/test_messages.vim
index 2dce6c6..c566bbc 100644
--- a/src/testdir/test_messages.vim
+++ b/src/testdir/test_messages.vim
@@ -386,7 +386,7 @@
 func Test_echo_verbose_system()
   CheckRunVimInTerminal
   CheckUnix    " needs the "seq" command
-  CheckNotMac  " doesn't use /tmp
+  CheckNotMac  " the macos TMPDIR is too long for snapshot testing
 
   let buf = RunVimInTerminal('', {'rows': 10})
   call term_sendkeys(buf, ":4 verbose echo system('seq 20')\<CR>")