revert: "fix(scripts): gen_terminfo clears Windows terminfo definitions #36736"

Problem:
`gen_terminfo.lua`'s output is unpredictable and depends on the system
ncurses version.

Invoking `tic` on `scripts/windows.ti` alone makes it use the system
terminfo definitions for the `use=…` fragments in `windows.ti` such as:

    use=xterm+256color, use=xterm+sl, use=xterm-new

This is particularly problematic on Debian, as they build ncurses with
`--with-xterm-kbs=del` [1], and thus some of the windows entries end up
with different definitions for `kTermKey_left`, which is almost
certainly not desired.

[1]: 2d238cf387/debian/rules (L149)

Solution:
This reverts commit 9f90992934.

src/gen/gen_terminfo.lua

@@ -123,8 +123,7 @@ if vim.uv.fs_stat(db) == nil then
   end
   sys('curl -O ' .. url)
   sys('gunzip -f terminfo.src.gz')
-  sys(('cat terminfo.src | tic -x -o "%s" -'):format(db))
-  sys(('cat scripts/windows.ti | tic -x -o "%s" -'):format(db))
+  sys(('cat terminfo.src scripts/windows.ti | tic -x -o "%s" -'):format(db))
   sys('rm -f terminfo.src')
 else
   print('using cached terminfo in ' .. db)