Remove several instances of duplicate "the" in comments (#12144)

Remove several instances of duplicate "the" in comments

src/blocked.c

@@ -650,7 +650,7 @@ static void unblockClientOnKey(client *c, robj *key) {
          * to run atomically, this is why we must enter the execution unit here before
          * running the command, and exit the execution unit after calling the unblock handler (if exists).
          * Notice that we also must set the current client so it will be available
-         * when we will try to send the the client side caching notification (done on 'afterCommand'). */
+         * when we will try to send the client side caching notification (done on 'afterCommand'). */
         client *old_client = server.current_client;
         server.current_client = c;
         enterExecutionUnit(1, 0);

src/commands/append.json

@@ -36,7 +36,7 @@
         ],
         "reply_schema": {
             "type": "integer",
-            "description": "The the length of the string after the append operation."
+            "description": "The length of the string after the append operation."
         },
         "arguments": [
             {

tests/unit/cluster/cli.tcl

@@ -64,7 +64,7 @@ start_multiple_servers 3 [list overrides $base_conf] {
     }
 
     test "Wait for cluster to be stable" {
-        # Cluster check just verifies the the config state is self-consistent,
+        # Cluster check just verifies the config state is self-consistent,
         # waiting for cluster_state to be okay is an independent check that all the
         # nodes actually believe each other are healthy, prevent cluster down error.
         wait_for_condition 1000 50 {