test(old): use Q -> gQ mapping instead of changing test when possible

src/nvim/testdir/setup.vim

@@ -30,6 +30,10 @@ set switchbuf=
 mapclear
 mapclear!
 
+" Make "Q" switch to Ex mode.
+" This does not work for all tests.
+nnoremap Q gQ
+
 " Prevent Nvim log from writing to stderr.
 let $NVIM_LOG_FILE = exists($NVIM_LOG_FILE) ? $NVIM_LOG_FILE : 'Xnvim.log'
 

src/nvim/testdir/test_substitute.vim

@@ -140,7 +140,7 @@ func Test_substitute_repeat()
   " This caused an invalid memory access.
   split Xfile
   s/^/x
-  call feedkeys("gQsc\<CR>y", 'tx')
+  call feedkeys("Qsc\<CR>y", 'tx')
   bwipe!
 endfunc
 

src/nvim/testdir/test_timers.vim

@@ -279,7 +279,7 @@ func Test_ex_mode()
   endfunc
   let timer = timer_start(40, function('g:Foo'), {'repeat':-1})
   " This used to throw error E749.
-  exe "normal gQsleep 100m\rvi\r"
+  exe "normal Qsleep 100m\rvi\r"
   call timer_stop(timer)
 endfunc