Update ARMv6 rootfs target OS to Debian 11

[directhex]

No description provided.

[am11]

@directhex, FYI, lower version in rootfs sandbox implies product binaries will be linked against old libc, which in turn implies greater compatibility for devices running older systems; as libc is known to provide run-time backward compatibility.

We chose Debian sid for riscv64 because it's a new port and still evolving from infancy. Unless something is broken on armv6 with older libc, it's good to stick with it as long as possible (e.g. we moved on from Ubuntu 14.04 'Trusty' two years after its standard support ended in 2019 #7694).

Note: the toolchain in base layer of docker can be on latest plan (e.g. llvm 18 which has better analyzers and codegen improvements etc.), while the rootfs can still stay at lowest possible version of libc.

[directhex]

We aren't shipping binaries for armv6, that's on the community, so there's no "runs on older customer systems" benefit for us

[am11]

We aren't shipping binaries for armv6, that's on the community, so there's no "runs on older customer systems" benefit for us

Right, it is on the same plan as other community platforms (freebsd, linux-{s390x,riscv64,ppcle64,loongarch64} etc.). Point was; if there is no benefit of updating the distro either (i.e. we are not relying on any new libc API or downgrading the functionality), leave it as-is?