Change spacetime_worker_wasm_instance_errors_total metric's labels

There are two purpose for introducing the changes in this commit:

1. Decrease the cardinality of the metric, as caller id and connection
   id combination would result in way too many combinations
2. Add a database_identity label, which is much more useful for the
   metric

Author: drogus

crates/core/src/host/wasm_common/module_host_actor.rs

@@ -473,12 +473,7 @@ impl InstanceCommon {
 
                 WORKER_METRICS
                     .wasm_instance_errors
-                    .with_label_values(
-                        &caller_identity,
-                        &self.info.module_hash,
-                        &caller_connection_id,
-                        procedure_name,
-                    )
+                    .with_label_values(&self.info.database_identity, &self.info.module_hash, procedure_name)
                     .inc();
 
                 // TODO(procedure-energy):
@@ -655,18 +650,12 @@ impl InstanceCommon {
     fn handle_outer_error(
         &mut self,
         energy: &EnergyStats,
-        caller_identity: &Identity,
-        caller_connection_id: &Option<ConnectionId>,
+        database_identity: Identity,
         reducer_name: &str,
     ) -> EventStatus {
         WORKER_METRICS
             .wasm_instance_errors
-            .with_label_values(
-                caller_identity,
-                &self.info.module_hash,
-                &caller_connection_id.unwrap_or(ConnectionId::ZERO),
-                reducer_name,
-            )
+            .with_label_values(&database_identity, &self.info.module_hash, reducer_name)
             .inc();
 
         if energy.remaining.get() == 0 {
@@ -782,7 +771,7 @@ impl InstanceCommon {
             Err(ExecutionError::User(err)) => {
                 inst.log_traceback("view", view_name, &anyhow::anyhow!(err));
 
-                self.handle_outer_error(&result.stats.energy, &caller_identity, &caller_connection_id, view_name)
+                self.handle_outer_error(&result.stats.energy, replica_ctx.database_identity, view_name)
                     .into()
             }
             Ok(res) => {

crates/core/src/worker_metrics/mod.rs

@@ -243,7 +243,7 @@ metrics_group!(
 
         #[name = spacetime_worker_wasm_instance_errors_total]
         #[help = "The number of fatal WASM instance errors, such as reducer panics."]
-        #[labels(caller_identity: Identity, module_hash: Hash, caller_connection_id: ConnectionId, reducer_symbol: str)]
+        #[labels(database_identity: Identity, module_hash: Hash, reducer_symbol: str)]
         pub wasm_instance_errors: IntCounterVec,
 
         #[name = spacetime_worker_wasm_memory_bytes]