Added a Builder for KeywordFieldType, removed redundant constructors

[Kubik42]

This is a follow up for #132962, where one of the feedbacks I got was to clean up KeywordFieldType's constructors.

I agree with this feedback. The constructors are very long and nearly identical. This makes them quite error prone and difficult to extend.

This PR addresses that by removing all but one constructor and replacing them with a Builder.

Note, I left behind one of the constructors as it was too messy to remove. The two classes that rely on it (ValuesSourceReaderBenchmark and EsPhysicalOperationProviders) can be reworked, but the end result is quite messy. Frankly, this mess is a consequence of how we're using the constructor in the first place. That being, we're creating a "builder" and bypassing the actual building in favor of using the builder as a data carrier, and then overriding a bunch of things that builder would've done for us. The workaround is to actually call builder.build(), but there are so nuances with needing to create a MapperBuilderContext for the builder to use, which I don't think is a good idea given that this is production and non-test code.

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[jordan-powers]

LGTM, thanks Dmitry!

[martijnvg]

This adds more production code than it removes and top of that there is another builder but now just for keyword field type.

I think the right change here is to remove the number of constructors here. Looks like 3 out of 5 constructors are exclusively used in tests. Let's try to reduce the number of constructors to just one or two. At best the rest of the constructors can be factory methods in testing code, or just removed.