Reduce CPU cycles spent on setting tracing tags

[RohanNagar]

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Addresses #3308 to avoid creating a RedisURI object when setting tracing tags. As explained in the issue, the current behavior results in unnecessary CPU usage.

This change caches the necessary information that is added to span tags each time the channel is registered.

This should work as long as the RedisUri attribute attached to the channel doesn't change (is that a correct assumption?).

The alternative is to just extract the information each time from channel.attr(ConnectionBuilder.REDIS_URI).get(). Something like:

        if (channel.hasAttr(ConnectionBuilder.REDIS_URI)) {
            String redisUriStr = channel.attr(ConnectionBuilder.REDIS_URI).get();
            span.tag("server.address", redisUriStr);
            span.tag("db.namespace", extractedDbValueFromRedisUriStr);
            span.tag("user.name", extractedUsernameValueFromRedisUriStr);
        }

[RohanNagar]

Hi @tishun I want to get your thoughts on this change - is it the right direction in order to address issue #3308? Thanks!