Increase local breaker reserve memory (#133770)

Currently, we use a local breaker that over-reserves memory for each 
driver to reduce frequent calls to the global circuit breaker, which can
be expensive.  After reviewing some profiles, the maximum reserved
amount appears too small and does not significantly reduce calls to the
global breaker.

The reserved amount should cover at least several pages of data (~256KB 
by default). This change proposes increasing the maximum reserved to two
pages (512KB).  One downside is that we may hit the circuit breaker
earlier under extremely tight memory conditions, but the impact should
be minimal. For example, on a node with 8 CPUs, the total reserved could
be 12 * 0.5 = 6MB. In cases with many long-running queries that
frequently wake and sleep, the extra over-reserved memory may be more
noticeable. However, even with 100 drivers, the total maximum would be
only 50MB.

Author: dnhatn

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/data/BlockFactory.java

@@ -19,10 +19,10 @@
 
 public class BlockFactory {
     public static final String LOCAL_BREAKER_OVER_RESERVED_SIZE_SETTING = "esql.block_factory.local_breaker.over_reserved";
-    public static final ByteSizeValue LOCAL_BREAKER_OVER_RESERVED_DEFAULT_SIZE = ByteSizeValue.ofKb(4);
+    public static final ByteSizeValue LOCAL_BREAKER_OVER_RESERVED_DEFAULT_SIZE = ByteSizeValue.ofKb(8);
 
     public static final String LOCAL_BREAKER_OVER_RESERVED_MAX_SIZE_SETTING = "esql.block_factory.local_breaker.max_over_reserved";
-    public static final ByteSizeValue LOCAL_BREAKER_OVER_RESERVED_DEFAULT_MAX_SIZE = ByteSizeValue.ofKb(16);
+    public static final ByteSizeValue LOCAL_BREAKER_OVER_RESERVED_DEFAULT_MAX_SIZE = ByteSizeValue.ofKb(512);
 
     public static final String MAX_BLOCK_PRIMITIVE_ARRAY_SIZE_SETTING = "esql.block_factory.max_block_primitive_array_size";
     public static final ByteSizeValue DEFAULT_MAX_BLOCK_PRIMITIVE_ARRAY_SIZE = ByteSizeValue.ofKb(512);