github,Cargo.toml: Strip release binaries using toolchain

From Rust 1.59, the cargo command is now able to strip a binary [1].
This can be enabled in Cargo.toml by adding a `strip = "true"` to
the `[profile.release]` section.

Adding such binary stripping support in Cargo.toml of the project,
also change the stripping process in the release workflow to the one
using toolchain, so that the AArch64 release binaries can also
be stripped.

Fixes: https://github.com/cloud-hypervisor/cloud-hypervisor/issues/4916

[1] https://doc.rust-lang.org/beta/cargo/reference/profiles.html#strip

Signed-off-by: Henry Wang <Henry.Wang@arm.com>
(cherry picked from commit 1ff0191b30)
Signed-off-by: Bo Chen <chen.bo@intel.com>

Cargo.toml

@@ -16,6 +16,7 @@ rust-version = "1.60"
 lto = true
 codegen-units = 1
 opt-level = "s"
+strip = true
 
 [dependencies]
 anyhow = "1.0.66"