Handle pipelined/multi cmds in cluster validator

What does this MR do and why?

This MR allows RedisClusterValidator to validate an array of commands instead of single commands. Array of commands are validated in the case of pipelines and transactions (MULTI) -- https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/instrumentation/redis_interceptor.rb#L15. To prepare for transition of redis-cache to redis cluster/distributed, we need to check and flag out pipeline/transactions which causes cross-slot errors.

See gitlab-com/gl-infra/scalability#2005 (closed)

TODO

• add allow_cross_slot_commands to areas of code which the validator now detects

Screenshots or screen recordings

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How to set up and validate locally

Before:

Loading development environment (Rails 6.1.6.1)
[1] pry(main)> Gitlab::Redis::Cache.with do |redis|
[1] pry(main)*   redis.multi do |multi|
[1] pry(main)*     multi.set('x', 1)
[1] pry(main)*     multi.set('y', 1)
[1] pry(main)*   end
[1] pry(main)* end
=> ["OK", "OK"]

After:

Loading development environment (Rails 6.1.6.1)
[1] pry(main)> Gitlab::Redis::Cache.with do |redis|
[1] pry(main)*   redis.multi do |multi|
[1] pry(main)*     multi.set('x', 1)
[1] pry(main)*     multi.set('y', 1)
[1] pry(main)*   end
[1] pry(main)* end
Gitlab::Instrumentation::RedisClusterValidator::CrossSlotError: Redis command PIPELINE/MULTI arguments hash to different slots. See https://docs.gitlab.com/ee/development/redis.html#multi-key-commands
from /Users/sylvesterchin/work/gitlab-development-kit/gitlab/lib/gitlab/instrumentation/redis_cluster_validator.rb:198:in `validate!'

MR acceptance checklist

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