Merge #5091

5091: Settings opt out r=Kerollmops a=ManyTheFish

# Pull Request

Related PRD: https://www.notion.so/meilisearch/API-usage-Settings-to-opt-out-indexing-features-fff4b06b651f8108ade3f858aeb16b14?pvs=4

## Related issue
Fixes #4979 

- [x] Add setting opt-out
- [x] Add analytics
- [x] Add tests


Co-authored-by: ManyTheFish <many@meilisearch.com>
Co-authored-by: Many the fish <many@meilisearch.com>

crates/milli/src/search/new/mod.rs

@@ -49,6 +49,7 @@ pub use self::geo_sort::Strategy as GeoSortStrategy;
 use self::graph_based_ranking_rule::Words;
 use self::interner::Interned;
 use self::vector_sort::VectorSort;
+use crate::index::PrefixSearch;
 use crate::localized_attributes_rules::LocalizedFieldIds;
 use crate::score_details::{ScoreDetails, ScoringStrategy};
 use crate::search::new::distinct::apply_distinct_rule;
@@ -68,6 +69,7 @@ pub struct SearchContext<'ctx> {
     pub term_interner: Interner<QueryTerm>,
     pub phrase_docids: PhraseDocIdsCache,
     pub restricted_fids: Option<RestrictedFids>,
+    pub prefix_search: PrefixSearch,
 }
 
 impl<'ctx> SearchContext<'ctx> {
@@ -85,6 +87,8 @@ impl<'ctx> SearchContext<'ctx> {
             }
         }
 
+        let prefix_search = index.prefix_search(txn)?.unwrap_or_default();
+
         Ok(Self {
             index,
             txn,
@@ -94,9 +98,14 @@ impl<'ctx> SearchContext<'ctx> {
             term_interner: <_>::default(),
             phrase_docids: <_>::default(),
             restricted_fids: None,
+            prefix_search,
         })
     }
 
+    pub fn is_prefix_search_allowed(&self) -> bool {
+        self.prefix_search != PrefixSearch::Disabled
+    }
+
     pub fn attributes_to_search_on(
         &mut self,
         attributes_to_search_on: &'ctx [String],

crates/milli/src/search/new/query_term/parse_query.rs

@@ -28,6 +28,7 @@ pub fn located_query_terms_from_tokens(
     words_limit: Option<usize>,
 ) -> Result<ExtractedTokens> {
     let nbr_typos = number_of_typos_allowed(ctx)?;
+    let allow_prefix_search = ctx.is_prefix_search_allowed();
 
     let mut query_terms = Vec::new();
 
@@ -94,7 +95,7 @@ pub fn located_query_terms_from_tokens(
                         ctx,
                         word,
                         nbr_typos(word),
-                        true,
+                        allow_prefix_search,
                         false,
                     )?;
                     let located_term = LocatedQueryTerm {