test: move oldtests to test directory (#22536)

The new oldtest directory is in test/old/testdir. The reason for this is
that many tests have hardcoded the parent directory name to be
'testdir'.

test/old/testdir/summarize.vim

@@ -0,0 +1,62 @@
+set cpo&vim
+if 1
+  " This is executed only with the eval feature
+  set nocompatible
+  set viminfo=
+  func Count(match, type)
+    if a:type ==# 'executed'
+      let g:executed += (a:match+0)
+    elseif a:type ==# 'failed'
+      let g:failed += a:match+0
+    elseif a:type ==# 'skipped'
+      let g:skipped += 1
+      call extend(g:skipped_output, ["\t" .. a:match])
+    endif
+  endfunc
+
+  let g:executed = 0
+  let g:skipped = 0
+  let g:failed = 0
+  let g:skipped_output = []
+  let g:failed_output = []
+  let output = [""]
+
+  if $TEST_FILTER != ''
+    call extend(g:skipped_output, ["\tAll tests not matching $TEST_FILTER: '" .. $TEST_FILTER .. "'"])
+  endif
+
+  try
+    " This uses the :s command to just fetch and process the output of the
+    " tests, it doesn't actually replace anything.
+    " And it uses "silent" to avoid reporting the number of matches.
+    silent %s/Executed\s\+\zs\d\+\ze\s\+tests\?/\=Count(submatch(0),'executed')/egn
+    silent %s/^SKIPPED \zs.*/\=Count(submatch(0), 'skipped')/egn
+    silent %s/^\(\d\+\)\s\+FAILED:/\=Count(submatch(1), 'failed')/egn
+
+    call extend(output, ["Skipped:"]) 
+    call extend(output, skipped_output)
+
+    call extend(output, [
+          \ "",
+          \ "-------------------------------",
+          \ printf("Executed: %5d Tests", g:executed),
+          \ printf(" Skipped: %5d Tests", g:skipped),
+          \ printf("  %s: %5d Tests", g:failed == 0 ? 'Failed' : 'FAILED', g:failed),
+          \ "",
+          \ ])
+    if filereadable('test.log')
+      " outputs and indents the failed test result
+      call extend(output, ["", "Failures: "])
+      let failed_output = filter(readfile('test.log'), { v,k -> !empty(k)})
+      call extend(output, map(failed_output, { v,k -> "\t".k}))
+      " Add a final newline
+      call extend(output, [""])
+    endif
+
+  catch  " Catch-all
+  finally
+    call writefile(output, 'test_result.log')  " overwrites an existing file
+  endtry
+endif
+
+q!