patch 8.2.0533: tests using term_wait() can still be flaky

Problem:    Tests using term_wait() can still be flaky.
Solution:   Increase the wait time when rerunning a test. (James McCoy,
            closes #5899)  Halve the initial times to make tests run faster
            when there is no rerun.

src/testdir/test_display.vim

@@ -174,7 +174,7 @@ func Test_scroll_CursorLineNr_update()
   call writefile(lines, filename)
   let buf = RunVimInTerminal('-S '.filename, #{rows: 5, cols: 50})
   call term_sendkeys(buf, "k")
-  call term_wait(buf)
+  call TermWait(buf)
   call VerifyScreenDump(buf, 'Test_winline_rnu', {})
 
   " clean up