chore: fix clippy lints from nightly-2025-03-16 (#11273)

I like to run nightly clippy every so often to make our future rust
upgrades easier. Some notable changes:

* Prefer `next_back()` over `last()`. Generic iterators will implement
`last()` to run forward through the iterator until the end.

* Prefer `io::Error::other()`.

* Use implicit returns

One case where I haven't dealt with the issues is the now
[more-sensitive "large enum variant"
lint](https://github.com/rust-lang/rust-clippy/pull/13833). I chose not
to take any decisions around it here, and simply marked them as allow
for now.

storage_broker/src/bin/storage_broker.rs

@@ -96,6 +96,7 @@ enum Message {
 
 impl Message {
     /// Convert proto message to internal message.
+    #[allow(clippy::result_large_err, reason = "TODO")]
     pub fn from(proto_msg: TypedMessage) -> Result<Self, Status> {
         match proto_msg.r#type() {
             MessageType::SafekeeperTimelineInfo => Ok(Message::SafekeeperTimelineInfo(
@@ -127,6 +128,7 @@ impl Message {
     }
 
     /// Get the tenant_timeline_id from the message.
+    #[allow(clippy::result_large_err, reason = "TODO")]
     pub fn tenant_timeline_id(&self) -> Result<Option<TenantTimelineId>, Status> {
         match self {
             Message::SafekeeperTimelineInfo(msg) => Ok(msg
@@ -185,6 +187,7 @@ enum SubscriptionKey {
 
 impl SubscriptionKey {
     /// Parse protobuf subkey (protobuf doesn't have fixed size bytes, we get vectors).
+    #[allow(clippy::result_large_err, reason = "TODO")]
     pub fn from_proto_subscription_key(key: ProtoSubscriptionKey) -> Result<Self, Status> {
         match key {
             ProtoSubscriptionKey::All(_) => Ok(SubscriptionKey::All),
@@ -195,6 +198,7 @@ impl SubscriptionKey {
     }
 
     /// Parse from FilterTenantTimelineId
+    #[allow(clippy::result_large_err, reason = "TODO")]
     pub fn from_proto_filter_tenant_timeline_id(
         opt: Option<&FilterTenantTimelineId>,
     ) -> Result<Self, Status> {
@@ -385,6 +389,7 @@ impl Registry {
     }
 
     /// Send msg to relevant subscribers.
+    #[allow(clippy::result_large_err, reason = "TODO")]
     pub fn send_msg(&self, msg: &Message) -> Result<(), Status> {
         PROCESSED_MESSAGES_TOTAL.inc();
 
@@ -436,6 +441,7 @@ struct Publisher {
 
 impl Publisher {
     /// Send msg to relevant subscribers.
+    #[allow(clippy::result_large_err, reason = "TODO")]
     pub fn send_msg(&mut self, msg: &Message) -> Result<(), Status> {
         self.registry.send_msg(msg)
     }

storage_broker/src/lib.rs

@@ -79,6 +79,7 @@ impl BrokerClientChannel {
 }
 
 // parse variable length bytes from protobuf
+#[allow(clippy::result_large_err, reason = "TODO")]
 pub fn parse_proto_ttid(proto_ttid: &ProtoTenantTimelineId) -> Result<TenantTimelineId, Status> {
     let tenant_id = TenantId::from_slice(&proto_ttid.tenant_id)
         .map_err(|e| Status::new(Code::InvalidArgument, format!("malformed tenant_id: {}", e)))?;