Skip rerank tests in mixed clusters (elastic#126415)

If the clusters don't support inference test services, skip tests that require inference services. 
Hence, we should check for rerank tests.

Relates elastic#123074

Author: dnhatn

x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/EsqlSpecTestCase.java

@@ -174,7 +174,7 @@ public final void test() throws Throwable {
     }
 
     protected void shouldSkipTest(String testName) throws IOException {
-        if (testCase.requiredCapabilities.contains("semantic_text_field_caps")) {
+        if (testCase.requiredCapabilities.contains("semantic_text_field_caps") || testCase.requiredCapabilities.contains("rerank")) {
             assumeTrue("Inference test service needs to be supported for semantic_text", supportsInferenceTestService());
         }
         checkCapabilities(adminClient(), testFeatureService, testName, testCase);