Improve `indices.query.bool.max_clause_count` in 7.x

[DaveCTurner]

In 8.x we configure the max_clause_count ergonomically (#81525) but this is not the case in 7.x. We'll continue to support 7.x for a long time yet, and we get rather a lot of escalations asking for approval to increase this value in these versions, sometimes at high urgency. What can we do to reduce the frequency of these escalations?

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[benwtrent]

We need to verify that the limitation calculation available in v8 is applicable in 7.x.

Related: #46433

Its tricky as some of the information we use in the calculation may only be available in the new Lucene version.

It would be really nice to update the calculation in 7.x.

@jpountz does this seem crazy or impossible to you?

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