Upgrade Rust to 1.52.0 (#17096)

* Upgrade Rust to 1.52.0
update nightly_version to newly pushed docker image
fix clippy lint errors
1.52 comes with grcov 0.8.0, include this version to script

* upgrade to Rust 1.52.1

* disabling Serum from downstream projects until it is upgraded to Rust 1.52.1

programs/bpf_loader/src/syscalls.rs

@@ -2810,6 +2810,8 @@ mod tests {
         let bytes1 = "Gaggablaghblagh!";
         let bytes2 = "flurbos";
 
+        // lint warns field addr and len "never read"
+        #[allow(dead_code)]
         struct MockSlice {
             pub addr: u64,
             pub len: usize,