Upgrade default image builder version

This commit upgrades the default CNB builder image from
cloudfoundry/cnb:0.0.43-bionic to cloudfoundry/cnb:0.0.53-bionic.
It also adds integration tests for the Maven and Gradle plugins
to verify both versions are supported.

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests-buildsImageWithV1Builder.gradle

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+ bootBuildImage {
+	 builder = "cloudfoundry/cnb:0.0.43-bionic"
+ }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests-failsWithBuilderError.gradle

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+ bootBuildImage {
+	 environment = ["BP_JAVA_VERSION" : "13.9.9"]
+ }