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_bufline.vim

@@ -164,7 +164,7 @@ func Test_appendbufline_redraw()
   END
   call writefile(lines, 'XscriptMatchCommon')
   let buf = RunVimInTerminal('-S XscriptMatchCommon', #{rows: 10})
-  call term_wait(buf)
+  call TermWait(buf)
   call VerifyScreenDump(buf, 'Test_appendbufline_1', {})
 
   call StopVimInTerminal(buf)