Remove knnSearchWithKOption as it makes no sense now

Author: carlosdelest

muted-tests.yml

@@ -511,9 +511,6 @@ tests:
 - class: org.elasticsearch.entitlement.runtime.policy.FileAccessTreeTests
   method: testWindowsAbsolutPathAccess
   issue: https://github.com/elastic/elasticsearch/issues/129168
-- class: org.elasticsearch.xpack.esql.qa.multi_node.EsqlSpecIT
-  method: test {knn-function.KnnSearchWithKOption ASYNC}
-  issue: https://github.com/elastic/elasticsearch/issues/129447
 - class: org.elasticsearch.xpack.ml.integration.ClassificationIT
   method: testWithDatastreams
   issue: https://github.com/elastic/elasticsearch/issues/129457
@@ -535,9 +532,6 @@ tests:
 - class: org.elasticsearch.xpack.security.PermissionsIT
   method: testWhenUserLimitedByOnlyAliasOfIndexCanWriteToIndexWhichWasRolledoverByILMPolicy
   issue: https://github.com/elastic/elasticsearch/issues/129481
-- class: org.elasticsearch.xpack.esql.qa.multi_node.EsqlSpecIT
-  method: test {knn-function.KnnSearchWithKOption SYNC}
-  issue: https://github.com/elastic/elasticsearch/issues/129512
 - class: org.elasticsearch.xpack.logsdb.qa.StandardVersusStandardReindexedIntoLogsDbChallengeRestIT
   method: testMatchAllQuery
   issue: https://github.com/elastic/elasticsearch/issues/129527

x-pack/plugin/esql/qa/testFixtures/src/main/resources/knn-function.csv-spec

@@ -29,25 +29,6 @@ chartreuse | [127.0, 255.0, 0.0]
 // end::knn-function-result[]
 ;
 
-knnSearchWithKOption
-required_capability: knn_function
-
-// tag::knn-function-options[]
-from colors metadata _score 
-| where knn(rgb_vector, [0,255,255], 140)
-| sort _score desc, color asc
-// end::knn-function-options[]
-| keep color, rgb_vector
-| limit 4
-;
-
-color:text  | rgb_vector:dense_vector
-cyan        | [0.0, 255.0, 255.0]
-turquoise   | [64.0, 224.0, 208.0]
-aqua marine | [127.0, 255.0, 212.0]
-teal        | [0.0, 128.0, 128.0]
-;
-
 # https://github.com/elastic/elasticsearch/issues/129550
 knnSearchWithSimilarityOption-Ignore
 required_capability: knn_function
@@ -63,7 +44,6 @@ pink       | [255.0, 192.0, 203.0]
 peach puff | [255.0, 218.0, 185.0]
 bisque     | [255.0, 228.0, 196.0]
 wheat      | [245.0, 222.0, 179.0]
-
 ;
 
 knnHybridSearch