Reduce number of threads used for BOMR library update checks

See gh-33824

Author: mhalbritter

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/UpgradeBom.java

@@ -68,7 +68,7 @@ public class UpgradeBom extends DefaultTask {
 
 	private String libraries;
 
-	private int threads = 8;
+	private int threads = 2;
 
 	@Inject
 	public UpgradeBom(BomExtension bom) {