'pastetoggle': Revert support for multi-key value (#6724)

Reverts commit 337b6179df

Closes #6716 at the expense of not being able to use a
multi-key 'pastetoggle' manually.

Multi-key 'pastetoggle' can still be used when inserting the entire
option into the typebuffer at once (though the use here is
questionable).

Also remove those tests to do with waiting for the completion of
'pastetoggle' and mention in the documentation that 'pastetoggle'
doesn't wait for timeout.

test/functional/options/pastetoggle_spec.lua

@@ -6,32 +6,35 @@ local command = helpers.command
 local eq = helpers.eq
 local eval = helpers.eval
 local sleep = helpers.sleep
+local expect = helpers.expect
 
 describe("'pastetoggle' option", function()
   before_each(function()
     clear()
     command('set nopaste')
-    command('set pastetoggle=a')
   end)
+
   it("toggles 'paste'", function()
-    eq(eval('&paste'), 0)
+    command('set pastetoggle=a')
+    eq(0, eval('&paste'))
     feed('a')
     -- Need another key so that the vgetorpeek() function returns.
     feed('j')
-    eq(eval('&paste'), 1)
+    eq(1, eval('&paste'))
   end)
-  it("multiple key 'pastetoggle' is waited for", function()
-    eq(eval('&paste'), 0)
-    local pastetoggle = 'lllll'
-    command('set pastetoggle=' .. pastetoggle)
-    command('set timeoutlen=1 ttimeoutlen=10000')
-    feed(pastetoggle:sub(0, 2))
-    -- sleep() for long enough that vgetorpeek() is gotten into, but short
-    -- enough that ttimeoutlen is not reached.
-    sleep(200)
-    feed(pastetoggle:sub(3, -1))
-    -- Need another key so that the vgetorpeek() function returns.
-    feed('j')
-    eq(eval('&paste'), 1)
+
+
+  it('does not wait for timeout', function()
+    command('set pastetoggle=abc')
+    command('set ttimeoutlen=9999999')
+    eq(0, eval('&paste'))
+    -- n.b. need <esc> to return from vgetorpeek()
+    feed('abc<esc>')
+    eq(1, eval('&paste'))
+    feed('ab')
+    sleep(10)
+    feed('c<esc>')
+    expect('bc')
+    eq(1, eval('&paste'))
   end)
 end)