[8.x] Backport muting SearchServiceSingleNodeTests (#126831)

* Mute org.elasticsearch.search.SearchServiceSingleNodeTests testBeforeShardLockDuringShardCreate #126812

* Mute org.elasticsearch.search.SearchServiceSingleNodeTests testLookUpSearchContext #126813

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Co-authored-by: elasticsearchmachine <58790826+elasticsearchmachine@users.noreply.github.com>

muted-tests.yml

@@ -454,3 +454,9 @@ tests:
 - class: org.elasticsearch.action.RejectionActionIT
   method: testSimulatedSearchRejectionLoad
   issue: https://github.com/elastic/elasticsearch/issues/125901
+- class: org.elasticsearch.search.SearchServiceSingleNodeTests
+  method: testBeforeShardLockDuringShardCreate
+  issue: https://github.com/elastic/elasticsearch/issues/126812
+- class: org.elasticsearch.search.SearchServiceSingleNodeTests
+  method: testLookUpSearchContext
+  issue: https://github.com/elastic/elasticsearch/issues/126813