Inline the generated Rust message Drop implementations

This allows the compiler to potentially optimize away unused message types more effectively, as demonstrated by the size reductions observed when unused messages are added in a test proto file.

PiperOrigin-RevId: 853529287

Author: protobuf-github-bot

src/google/protobuf/compiler/rust/message.cc

@@ -741,6 +741,7 @@ void GenerateRs(Context& ctx, const Descriptor& msg, const upb::DefPool& pool) {
         //~ We implement drop unconditionally, so that `$Msg$: Drop` regardless
         //~ of kernel.
         impl $std$::ops::Drop for $Msg$ {
+          #[inline]
           fn drop(&mut self) {
             $Msg::drop$
           }