Breaking change of default of max_number_of_snapshots in v8

[DaveCTurner]

In #64461 we introduced the ability to set a limit on the number of snapshots in a repo, but in the backport to 7.11 we set the limit to Integer.MAX_VALUE to avoid introducing a breaking change in this minor release. However, the limit reduces to 500 in 8.0 which now represents a future breaking change. Today this change gets no mention in the 8.0 breaking changes docs, nor a deprecation warning in 7.x to help users prepare for it.

For changes to parameter defaults we'd usually require users to set the parameter explicitly to avoid the deprecation warning. I'm not sure that works in this case, if we say "you must set max_number_of_snapshots" then users will explicitly set it too high to work around their current snapshot hygiene problems, rather than dealing with the root cause.

[elasticmachine]

Pinging @elastic/es-distributed (Team:Distributed)

[repantis]

Removing the blocker label, per @DaveCTurner's suggestion, since 8.0.0 shipped without this fix, but still tracking this as a bug.

[Leaf-Lin]

As of #74350, @original-brownbear has improved the max_numbef_of_snapshots in v8. There was a doc PR on the removal of the soft limit.

What's still needed to be done on this issue?

[original-brownbear]

I don't think there's anything left to be done here, we went for no limit now and improved scalability instead.