Prevent long value saturation within scaled_float mappings

[benwtrent]

It is easy to have long value saturation and overflow with scaled_float and allowing users to saturate longs seems dangerous and confusing.

I would generally expect any saturation to be an input error by the user as it will then break subsequent queries against the field (see example range query in the issue).

This commit allows saturation to occur if the index was created in a previous version or if ignore_malformed: true.

closes: #105361

[elasticsearchmachine]

Pinging @elastic/es-search (Team:Search)

[javanna]

I was wondering if we consider this a bugfix or an enhancement (the corresponding label is missing), as that would affect the bwc strategy.

[benwtrent]

@javanna I do not know. But using range queries (one of the main reasons to have scaled_float) over saturated values just doesn't work.

We can update the docs separately to ensure that folks know this.

[nik9000]

I like the idea of failing but I don't know if we're ok with the semi-breaking nature. Opting folks into rejecting documents just by upgrading seems like something dangerous at this point.

[benwtrent]

Opting folks into rejecting documents just by upgrading seems like something dangerous at this point.

I understand these concerns.

We can just document, "Hey, don't do this".

I definitely don't want to add a new parameter, and ignore_malformed seemed to fit this situation.

What do y'all think of adding a deprecation here? Seems like we should warn users and they shouldn't be doing this and if they want to keep doing it, they gotta allow ignore_malformed. @nik9000 @javanna

[benwtrent]

For now, I am going to close this PR and create another one that is a docs update. We should be very clear, that saturation can happen and can return weirdness. Simply saying "hey, these fit in a long value" isn't enough for typical users.