[Profiling] Fix ES queries for serverless (elastic#130624)

* [Profiling] Fix ES queries for serverless

* Remove Resampler and its tests

* Remove the final keyword from local variables

Author: rockdaboot

x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/action/GetStackTracesRequest.java

@@ -398,8 +398,8 @@ public boolean equals(Object o) {
     public int hashCode() {
         // The object representation of `query` may use Lucene's ByteRef to represent values. This class' hashCode implementation
         // uses StringUtils.GOOD_FAST_HASH_SEED which is reinitialized for each JVM. This means that hashcode is consistent *within*
-        // a JVM but will not be consistent across the cluster. As we use hashCode e.g. to initialize the random number generator in
-        // Resampler to produce a consistent downsampling results, relying on the default hashCode implementation of `query` will
+        // a JVM but will not be consistent across the cluster. As we use hashCode to initialize random number generators
+        // to produce consistent downsampling results, relying on the default hashCode implementation of `query` will
         // produce consistent results per node but not across the cluster. To avoid this, we produce the hashCode based on the
         // string representation instead, which will produce consistent results for the entire cluster and across node restarts.
         return Objects.hash(Objects.toString(query, "null"), sampleSize, Arrays.hashCode(indices), stackTraceIdsField);

x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/action/GetStackTracesResponseBuilder.java

@@ -20,6 +20,7 @@ class GetStackTracesResponseBuilder {
     private Map<TraceEventID, TraceEvent> stackTraceEvents;
     private double samplingRate;
     private long totalSamples;
+    private long samplingFrequency;
     private Double requestedDuration;
     private final Double awsCostFactor;
     private final Double azureCostFactor;
@@ -155,4 +156,12 @@ public GetStackTracesResponse build() {
         }
         return new GetStackTracesResponse(stackTraces, stackFrames, executables, stackTraceEvents, totalFrames, samplingRate, totalSamples);
     }
+
+    public void setSamplingFrequency(long samplingFrequency) {
+        this.samplingFrequency = samplingFrequency;
+    }
+
+    public long getSamplingFrequency() {
+        return samplingFrequency;
+    }
 }