Fix conditions that lead to auto-configure PushGateway

See gh-22919

Author: smlc

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/prometheus/PrometheusMetricsExportAutoConfigurationTests.java

@@ -154,6 +154,12 @@ void withCustomPushGatewayURL() {
 				.run((context) -> hasGatewayURL(context, "https://example.com:8080/metrics/"));
 	}
 
+	@Test
+	void pushGatewayIsNotConfiguredWhenEnabledFlagIsNotSet() {
+		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
+				.run((context) -> assertThat(context).doesNotHaveBean(PrometheusPushGatewayManager.class));
+	}
+
 	private void hasGatewayURL(AssertableApplicationContext context, String url) {
 		assertThat(context).hasSingleBean(PrometheusPushGatewayManager.class);
 		PrometheusPushGatewayManager gatewayManager = context.getBean(PrometheusPushGatewayManager.class);

spring-boot-project/spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -1552,13 +1552,12 @@ To enable Prometheus Pushgateway support, add the following dependency to your p
 </dependency>
 ----
 
-When the Prometheus Pushgateway dependency is present on the classpath, Spring Boot auto-configures a `PrometheusPushGatewayManager` bean.
+When the Prometheus Pushgateway dependency is present on the classpath and the `configprop:management.metrics.export.prometheus.pushgateway.enabled` property is set to true, a PrometheusPushGatewayManager bean is auto-configured.
 This manages the pushing of metrics to a Prometheus Pushgateway.
 The `PrometheusPushGatewayManager` can be tuned using properties under `management.metrics.export.prometheus.pushgateway`.
 For advanced configuration, you can also provide your own `PrometheusPushGatewayManager` bean.
 
 
-
 [[production-ready-metrics-export-signalfx]]
 ==== SignalFx
 SignalFx registry pushes metrics to {micrometer-registry-docs}/signalFx[SignalFx] periodically.