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.
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
index b7893ff..a1c7b98 100644
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -402,7 +402,7 @@
 
   call writefile(lines, 'Xpumscript')
   let buf = RunVimInTerminal('-S Xpumscript', #{rows: 10})
-  call term_wait(buf, 100)
+  call TermWait(buf, 50)
   call term_sendkeys(buf, "a\<C-N>")
   call VerifyScreenDump(buf, 'Test_pum_with_folds_two_tabs', {})
 
@@ -427,9 +427,9 @@
 
   call writefile(lines, 'Xpreviewscript')
   let buf = RunVimInTerminal('-S Xpreviewscript', #{rows: 12})
-  call term_wait(buf, 100)
+  call TermWait(buf, 50)
   call term_sendkeys(buf, "Gi\<C-X>\<C-O>")
-  call term_wait(buf, 200)
+  call TermWait(buf, 100)
   call term_sendkeys(buf, "\<C-N>")
   call VerifyScreenDump(buf, 'Test_pum_with_preview_win', {})