ci: Move dist-aarch64-linux to an aarch64 runner

[mrkajetanp]

Move the dist-aarch64-linux CI job to an aarch64 runner instead of cross-compiling it from an x86 one. This will make it possible to perform optimisations such as LTO, PGO and BOLT later on.

r? @Kobzol

try-job: dist-aarch64-linux

[Kobzol]

First let's see if it works, and what's the time impact :)

@bors try

[bors]

⌛ Trying commit 4122380 with merge 6b8022e...

[bors]

☀️ Try build successful - checks-actions
Build commit: 6b8022e (6b8022ef4cbfc68ca42d9ec189f62d4c129e8685)

[Kobzol]

@bors try

[bors]

⌛ Trying commit 4122380 with merge 3521911...

[bors]

☀️ Try build successful - checks-actions
Build commit: 3521911 (352191141fb3c2d284583d558f204d3299a4f7f6)

[Kobzol]

The cached duration now seems to be ~1h 20m. Before, it was approximately ~1h 50m, although on a free runner.

[mrkajetanp]

Before meaning when it was running on the x86 runner? That would make sense given that it had to build the whole cross-compiling toolchain first I suppose.

[Kobzol]

Yeah, before meaning when it was cross-compiling, and also running on a 4-core machine (vs now running on a 8-core machine). The costs of the ARM machine is quite different to us than the previous machine though, so we'll need to discuss this in the infra team.

[mrkajetanp]

Fair enough, best of luck! :)