Update synthetic source documentation for all field types

[salvatore-campagna]

Description

Synthetic source documentation is still out of sync after all improvements we introduced in Elasticsearch 8.15 and above.

For instance the date nanos documentation says the following

date_nanos fields support [synthetic _source](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-source-field.html#synthetic-source) in their default configuration. Synthetic _source cannot be used together with [copy_to](https://www.elastic.co/guide/en/elasticsearch/reference/current/copy-to.html), [ignore_malformed](https://www.elastic.co/guide/en/elasticsearch/reference/current/ignore-malformed.html) set to true or with [doc_values](https://www.elastic.co/guide/en/elasticsearch/reference/current/doc-values.html) disabled.

which does not reflect how date nanos works in synthetic source when used together ignore_malformed.

We need to go through each and every field type and check documentation reflects our improvements in synthetic source.

[elasticsearchmachine]

Pinging @elastic/es-docs (Team:Docs)

[elasticsearchmachine]

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