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_popup.vim b/src/testdir/test_popup.vim
index 4ca35b2..e96d5fd 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -683,11 +683,11 @@
 
   call term_sendkeys(buf, "Gi\<c-x>")
   call term_sendkeys(buf, "\<c-v>")
-  call term_wait(buf, 100)
+  call TermWait(buf, 50)
   " popup first entry "!" must be at the top
   call WaitForAssert({-> assert_match('^!\s*$', term_getline(buf, 1))})
   exe 'resize +' . (h - 1)
-  call term_wait(buf, 100)
+  call TermWait(buf, 50)
   redraw!
   " popup shifted down, first line is now empty
   call WaitForAssert({-> assert_equal('', term_getline(buf, 1))})
@@ -750,11 +750,11 @@
   let buf = RunVimInTerminal('-S Xscript', {})
 
   " wait for the script to finish
-  call term_wait(buf)
+  call TermWait(buf)
 
   " Test that popup and previewwindow do not overlap.
   call term_sendkeys(buf, "o")
-  call term_wait(buf, 100)
+  call TermWait(buf, 50)
   call term_sendkeys(buf, "\<C-X>\<C-N>")
   call VerifyScreenDump(buf, 'Test_popup_and_previewwindow_01', {})