testing/vaultwarden: upstream build settings

It aint much but its honest work

• CARGO_PROFILE_RELEASE_LTO is already set to thin on Cargo.toml, source
• Set VW_VERSION because we dont have the git history, source

I thought I could remove the mimalloc part but after compare the builds its better to keep it

If we strip symbols and abort on panic, it can be produce smaller binary, but Im not sure if worth to do it