Ctrl+Shift+F6 to show config doesn't work with LESS=F

[trygveaa]

Describe the bug
I have set LESS=FRS in my environment, which causes less to exit if less than one page is printed. This causes Ctrl+Shift+F6 to just blink the screen, since less exits immediately.

To Reproduce
Steps to reproduce the behavior:

1. Set LESS=F in your environment and make sure scrollback_pager is the default, or at least is less and doesn't unset F. Or alternatively just set scrollback_pager less -F
2. Press Ctrl+Shift+F6.
3. Observe that kitty just blinks instead of showing the config,

Environment details
I ran kitty with --config NONE.

kitty 0.21.1 created by Kovid Goyal
Linux george 5.12.10-arch1-1 #1 SMP PREEMPT Thu, 10 Jun 2021 16:34:50 +0000 x86_64
Arch Linux \r (\l)
LSB_VERSION=1.4
DISTRIB_ID=Arch
DISTRIB_RELEASE=rolling
DISTRIB_DESCRIPTION="Arch Linux"
Running under:X11

Config options different from defaults: