Relax profiles assertions (elastic#123919) (elastic#123942)

If the final driver is woken up before the exchange buffer is finished, 
there will be two sleeps in its profile instead of one. We don't need
these assertions to be so precise. This change relaxes the assertions to
allow reduce operators to have more than one sleep.

Closes elastic#123210

Author: dnhatn

x-pack/plugin/esql/qa/server/single-node/src/javaRestTest/java/org/elasticsearch/xpack/esql/qa/single_node/RestEsqlIT.java

@@ -493,26 +493,16 @@ public void testForceSleepsProfile() throws IOException {
             if (operators.contains("LuceneSourceOperator")) {
                 assertMap(sleeps, matchesMap().entry("counts", Map.of()).entry("first", List.of()).entry("last", List.of()));
             } else if (operators.contains("ExchangeSourceOperator")) {
-                if (operators.contains("ExchangeSinkOperator")) {
-                    assertMap(sleeps, matchesMap().entry("counts", matchesMap().entry("exchange empty", greaterThan(0))).extraOk());
-                    @SuppressWarnings("unchecked")
-                    List<Map<String, Object>> first = (List<Map<String, Object>>) sleeps.get("first");
-                    for (Map<String, Object> s : first) {
-                        assertMap(s, sleepMatcher);
-                    }
-                    @SuppressWarnings("unchecked")
-                    List<Map<String, Object>> last = (List<Map<String, Object>>) sleeps.get("last");
-                    for (Map<String, Object> s : last) {
-                        assertMap(s, sleepMatcher);
-                    }
-
-                } else {
-                    assertMap(
-                        sleeps,
-                        matchesMap().entry("counts", matchesMap().entry("exchange empty", 1))
-                            .entry("first", List.of(sleepMatcher))
-                            .entry("last", List.of(sleepMatcher))
-                    );
+                assertMap(sleeps, matchesMap().entry("counts", matchesMap().entry("exchange empty", greaterThan(0))).extraOk());
+                @SuppressWarnings("unchecked")
+                List<Map<String, Object>> first = (List<Map<String, Object>>) sleeps.get("first");
+                for (Map<String, Object> s : first) {
+                    assertMap(s, sleepMatcher);
+                }
+                @SuppressWarnings("unchecked")
+                List<Map<String, Object>> last = (List<Map<String, Object>>) sleeps.get("last");
+                for (Map<String, Object> s : last) {
+                    assertMap(s, sleepMatcher);
                 }
             } else {
                 fail("unknown signature: " + operators);