Align metric function name with metric's name (informalsystems#1607)

- fn `ibc_client_update` is the only fn which has a slightly different
name with the metrics it emits
- renaming it to its metrics name improves the readability of the code

relayer/src/worker/client.rs

@@ -70,7 +70,7 @@ impl<ChainA: ChainHandle, ChainB: ChainHandle> ClientWorker<ChainA, ChainB> {
                 match client.refresh() {
                     Ok(Some(_)) => {
                         telemetry!(
-                            ibc_client_update,
+                            ibc_client_updates,
                             &self.client.dst_chain_id,
                             &self.client.dst_client_id,
                             1

telemetry/src/state.rs

@@ -65,7 +65,7 @@ impl TelemetryState {
     }
 
     /// Update the number of client updates per client
-    pub fn ibc_client_update(&self, chain: &ChainId, client: &ClientId, count: u64) {
+    pub fn ibc_client_updates(&self, chain: &ChainId, client: &ClientId, count: u64) {
         let labels = &[
             KeyValue::new("chain", chain.to_string()),
             KeyValue::new("client", client.to_string()),