patch 8.2.4078: terminal test for current directory not used on FreeBSD

Problem:    Terminal test for current directory not used on FreeBSD.
Solution:   Make it work on FreeBSD. (Ozaki Kiichi, closes #9516) Add
            TermWait() inside Run_shell_in_terminal() as a generic solution.
diff --git a/src/testdir/test_terminal3.vim b/src/testdir/test_terminal3.vim
index a351799..5e7a89f 100644
--- a/src/testdir/test_terminal3.vim
+++ b/src/testdir/test_terminal3.vim
@@ -779,8 +779,6 @@
 func Test_terminal_sync_shell_dir()
   CheckUnix
   " The test always use sh (see src/testdir/unix.vim).
-  " However, BSD's sh doesn't seem to play well with OSC 7 escape sequence.
-  CheckNotBSD
 
   set asd
   " , is
@@ -789,15 +787,15 @@
   let chars = ",a"
   " "," is url-encoded as '%2C'
   let chars_url = "%2Ca"
-  let tmpfolder = fnamemodify(tempname(),':h').'/'.chars
-  let tmpfolder_url = fnamemodify(tempname(),':h').'/'.chars_url
+  let tmpfolder = fnamemodify(tempname(),':h') .. '/' .. chars
+  let tmpfolder_url = fnamemodify(tempname(),':h') .. '/' .. chars_url
   call mkdir(tmpfolder, "p")
   let buf = Run_shell_in_terminal({})
-  call term_sendkeys(buf, "echo -ne $'\\e\]7;file://".tmpfolder_url."\\a'\<CR>")
-  "call term_sendkeys(buf, "cd ".tmpfolder."\<CR>")
+  call term_sendkeys(buf, "echo $'\\e\]7;file://" .. tmpfolder_url .. "\\a'\<CR>")
+  "call term_sendkeys(buf, "cd " .. tmpfolder .. "\<CR>")
   call TermWait(buf)
   if has("mac")
-    let expected = "/private".tmpfolder
+    let expected = "/private" .. tmpfolder
   else
     let expected = tmpfolder
   endif