[Feature] Provide legacy_lz4 GKI about kernelsu

[hobby1999]

use this,https://kernelsu.org/guide/installation.html#patch-boot-image

[onokatio]

use this,https://kernelsu.org/guide/installation.html#patch-boot-image

Yes, I know and am using it. But I want prebuilt images.

[apprehensions]

What is wrong with LMK?

[onokatio]

LMK is good for daily use.
But installation LKM by fastboot flash doesn't make stock image backup on kernelsu app, so I can't use restore stock feature in app.
So I woule like to use GKI boot.img to get temporary root to install LKM by app.

[onokatio]

I'm trying to inspect, but I found that repacking boot.img with magiskboot and provided android?-boot-lz4.img from kernelsu are almost same.
I couldn't find about "compression format" diffirence.

[onokatio]

And also I found that two file are diffirence only about avb header. I think this means true reason that kernelsu gki doesn't boot pixel is not relating compression format.

[onokatio]

umm, It seems bootloop is from just vbmeta mismatch.