[stable/redis-ha] Add option to disable commands in redis config

[lord-kyron]

What this PR does / why we need it:

We need this PR as it seems when an attempt is made to enter the "rename-command" key more than once in the config, this is impossible as the key is marked as duplicated. But this blocks us from using rename-command to disable FLUSHALL and FLUSHDB commands at the same time.

Which issue this PR fixes

n/a

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x] DCO signed
• [x] Chart Version bumped
• [x] Variables are documented in the README.md
• [x] Title of the PR starts with chart name (e.g. [stable/mychartname])

[lord-kyron]

@DandyDeveloper please, take a look at this as our organization needs this feature otherwise we cannot use the rename-command in the config as it is being treated as duplicated key when mentioned multiple times. Thanks!

[lord-kyron]

@DandyDeveloper ?

[DandyDeveloper]

@lord-kyron The only thing I might end up rolling back is the defaults. It's a good addition but its plausible existing users might be consuming these and for them to "suddenly" not work using this could be concerning. For now though, I think these are solid defaults. Merging.