chore(redis): set max active redis connections to 1000 (#63718)

When active client is 0, there is no limit to the amount of active
clients which can lead to Redis quickly reaching it's MaxClient (10000
by default)

For more context see [this slack
thread](https://sourcegraph.slack.com/archives/C05EMJM2SLR/p1720448507809479)

## Test plan
CI


## Changelog
* redis-pool: set max active clients to 1000
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internal/redispool/redispool.go

@@ -81,6 +81,7 @@ func dialRedis(rawEndpoint string) (redis.Conn, error) {
 var Cache = NewKeyValue(addresses.Cache, &redis.Pool{
 	MaxIdle:     3,
 	IdleTimeout: 240 * time.Second,
+	MaxActive:   1000,
 })
 
 // Store is a redis configured for persisting data. Do not abuse this pool,
@@ -90,4 +91,5 @@ var Cache = NewKeyValue(addresses.Cache, &redis.Pool{
 var Store = NewKeyValue(addresses.Store, &redis.Pool{
 	MaxIdle:     10,
 	IdleTimeout: 240 * time.Second,
+	MaxActive:   1000,
 })