test: improve editor/fold_spec.lua and editor/put_spec.lua (#22916)

- Close and open a new window each time so that window options have
  their default values in each test.
- Change feed_command() to command() as the latter is faster.

test/functional/ui/fold_spec.lua

@@ -4,7 +4,6 @@ local clear, feed, eq = helpers.clear, helpers.feed, helpers.eq
 local command = helpers.command
 local feed_command = helpers.feed_command
 local insert = helpers.insert
-local expect = helpers.expect
 local funcs = helpers.funcs
 local meths = helpers.meths
 local exec = helpers.exec
@@ -2023,29 +2022,4 @@ describe("folded lines", function()
   describe('without ext_multigrid', function()
     with_ext_multigrid(false)
   end)
-
-  it('no folds remains if :delete makes buffer empty #19671', function()
-    funcs.setline(1, {'foo', 'bar', 'baz'})
-    command('2,3fold')
-    command('%delete')
-    eq(0, funcs.foldlevel(1))
-  end)
-
-  it('multibyte fold markers work #20438', function()
-    exec([[
-      setlocal foldmethod=marker
-      setlocal foldmarker=«,»
-      setlocal commentstring=/*%s*/
-    ]])
-    insert([[
-      bbbbb
-      bbbbb
-      bbbbb]])
-    feed('zfgg')
-    expect([[
-      bbbbb/*«*/
-      bbbbb
-      bbbbb/*»*/]])
-    eq(1, funcs.foldlevel(1))
-  end)
 end)