chore(backend): fix flaky test that made wrong assumptions about order being guaranteed

backend/src/test/kotlin/org/loculus/backend/controller/submission/DeleteSequencesEndpointTest.kt

@@ -1,13 +1,16 @@
 package org.loculus.backend.controller.submission
 
-import org.hamcrest.CoreMatchers.containsString
-import org.hamcrest.CoreMatchers.hasItem
-import org.hamcrest.CoreMatchers.`is`
-import org.hamcrest.CoreMatchers.not
 import org.hamcrest.MatcherAssert.assertThat
+import org.hamcrest.Matchers.allOf
+import org.hamcrest.Matchers.containsInAnyOrder
+import org.hamcrest.Matchers.containsString
 import org.hamcrest.Matchers.equalTo
+import org.hamcrest.Matchers.hasEntry
+import org.hamcrest.Matchers.hasItem
 import org.hamcrest.Matchers.hasProperty
 import org.hamcrest.Matchers.hasSize
+import org.hamcrest.Matchers.`is`
+import org.hamcrest.Matchers.not
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.params.ParameterizedTest
 import org.junit.jupiter.params.provider.MethodSource
@@ -309,6 +312,13 @@ class DeleteSequencesEndpointTest(
             )
             .submissionIdMappings
 
+        val expectedPairs = accessionVersions.map { entry ->
+            allOf(
+                hasEntry("accession", entry.accession),
+                hasEntry("version", entry.version.toInt()),
+            )
+        }
+
         client.deleteSequenceEntries(
             scope = ALL,
             accessionVersionsFilter = accessionVersions,
@@ -317,8 +327,7 @@ class DeleteSequencesEndpointTest(
             .andExpect(status().isOk)
             .andExpect(content().contentType(MediaType.APPLICATION_JSON_VALUE))
             .andExpect(jsonPath("\$.length()").value(accessionVersions.size))
-            .andExpect(jsonPath("\$[0].accession").value(accessionVersions.first().accession))
-            .andExpect(jsonPath("\$[0].version").value(accessionVersions.first().version))
+            .andExpect(jsonPath("\$[*]", containsInAnyOrder(*expectedPairs.toTypedArray())))
     }
 
     @Test