perf: trim tracer E2E workload to single function (repeatString)

Keep only repeatString which reliably produces 284% improvement.
Drop computeSum (marginal 16%), filterEvens and instanceMethod (no
optimization found). Reduces tracer E2E from ~1h27m to ~21m.

Author: KRRT7

tests/test_languages/fixtures/java_tracer_e2e/src/main/java/com/example/Workload.java

@@ -1,18 +1,7 @@
 package com.example;
 
-import java.util.ArrayList;
-import java.util.List;
-
 public class Workload {
 
-    public static int computeSum(int n) {
-        int sum = 0;
-        for (int i = 0; i < n; i++) {
-            sum += i;
-        }
-        return sum;
-    }
-
     public static String repeatString(String s, int count) {
         String result = "";
         for (int i = 0; i < count; i++) {
@@ -21,46 +10,15 @@ public static String repeatString(String s, int count) {
         return result;
     }
 
-    public static List<Integer> filterEvens(List<Integer> numbers) {
-        List<Integer> result = new ArrayList<>();
-        for (int n : numbers) {
-            if (n % 2 == 0) {
-                result.add(n);
-            }
-        }
-        return result;
-    }
-
-    public int instanceMethod(int x, int y) {
-        return x * y + computeSum(x);
-    }
-
     public static void main(String[] args) {
-        // Run methods with large inputs so JFR can capture CPU samples.
-        // Small inputs finish too fast (<1ms) for JFR's 10ms sampling interval.
+        // Run with large inputs so JFR can capture CPU samples.
         for (int round = 0; round < 1000; round++) {
-            computeSum(100_000);
             repeatString("hello world ", 1000);
-
-            List<Integer> nums = new ArrayList<>();
-            for (int i = 1; i <= 10_000; i++) nums.add(i);
-            filterEvens(nums);
-
-            Workload w = new Workload();
-            w.instanceMethod(100_000, 42);
         }
 
         // Also call with small inputs for variety in traced args
-        System.out.println("computeSum(100) = " + computeSum(100));
         System.out.println("repeatString(\"ab\", 3) = " + repeatString("ab", 3));
 
-        List<Integer> small = new ArrayList<>();
-        for (int i = 1; i <= 10; i++) small.add(i);
-        System.out.println("filterEvens(1..10) = " + filterEvens(small));
-
-        Workload w = new Workload();
-        System.out.println("instanceMethod(5, 3) = " + w.instanceMethod(5, 3));
-
         System.out.println("Workload complete.");
     }
 }