docs: remove private links as these are public-facing docs

PiperOrigin-RevId: 387823959

google/cloud/retail/v2alpha/search_service.proto

@@ -570,8 +570,7 @@ message SearchRequest {
 
   // The filter syntax consists of an expression language for constructing a
   // predicate from one or more fields of the products being filtered. Filter
-  // expression is case-sensitive. See more details at this [user
-  // guide](/retail/private/docs/filter-and-order#filter).
+  // expression is case-sensitive.
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string filter = 10;
@@ -590,9 +589,7 @@ message SearchRequest {
 
   // The order in which products are returned. Products can be ordered by
   // a field in an [Product][google.cloud.retail.v2alpha.Product] object. Leave
-  // it unset if ordered by relevance. OrderBy expression is case-sensitive. See
-  // more details at this [user
-  // guide](/retail/private/docs/filter-and-order#order).
+  // it unset if ordered by relevance. OrderBy expression is case-sensitive.
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string order_by = 11;
@@ -611,22 +608,19 @@ message SearchRequest {
   // facet feature.
   DynamicFacetSpec dynamic_facet_spec = 21;
 
-  // Boost specification to boost certain products. See more details at this
-  // [user guide](/retail/private/docs/boosting).
+  // Boost specification to boost certain products.
   BoostSpec boost_spec = 13;
 
   // The query expansion specification that specifies the conditions under which
-  // query expansion will occur. See more details at this [user
-  // guide](/retail/private/docs/result-size#query_expansion).
+  // query expansion will occur.
   QueryExpansionSpec query_expansion_spec = 14;
 
   // The relevance threshold of the search results.
   //
   // Defaults to
   // [RelevanceThreshold.HIGH][google.cloud.retail.v2alpha.SearchRequest.RelevanceThreshold.HIGH],
   // which means only the most relevant results are shown, and the least number
-  // of results are returned. See more details at this [user
-  // guide](/retail/private/docs/result-size#relevance_thresholding).
+  // of results are returned.
   RelevanceThreshold relevance_threshold = 15;
 
   // The keys to fetch and rollup the matching