Polish documentation

* Remove double occurrence of InfluxDbHealthIndicator.
* Fix JUnit 5 `@ExtendWith` references
* Use consistent casing of HtmlUnit.

See spring-projectsgh-18718

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

@@ -688,9 +688,6 @@ The following `HealthIndicators` are auto-configured by Spring Boot when appropr
 | {spring-boot-actuator-module-code}/influx/InfluxDbHealthIndicator.java[`InfluxDbHealthIndicator`]
 | Checks that an InfluxDB server is up.
 
-| {spring-boot-actuator-module-code}/influx/InfluxDbHealthIndicator.java[`InfluxDbHealthIndicator`]
-| Checks that an InfluxDB server is up.
-
 | {spring-boot-actuator-module-code}/jms/JmsHealthIndicator.java[`JmsHealthIndicator`]
 | Checks that a JMS broker is up.
 

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

@@ -5920,7 +5920,7 @@ The annotation works by <<boot-features-testing-spring-boot-applications-detecti
 In addition to `@SpringBootTest` a number of other annotations are also provided for <<boot-features-testing-spring-boot-applications-testing-autoconfigured-tests,testing more specific slices>> of an application.
 
 TIP: If you are using JUnit 4, don't forget to also add `@RunWith(SpringRunner.class)` to your test, otherwise the annotations will be ignored.
-If you are using JUnit 5, there's no need to add the equivalent `@RunWith(SpringExtension.class)` as `@SpringBootTest` and the other `@…Test` annotations are already annotated with it.
+If you are using JUnit 5, there's no need to add the equivalent `@ExtendWith(SpringExtension.class)` as `@SpringBootTest` and the other `@…Test` annotations are already annotated with it.
 
 By default, `@SpringBootTest` will not start a server.
 You can use the `webEnvironment` attribute of `@SpringBootTest` to further refine how your tests run:
@@ -6315,7 +6315,7 @@ The following example uses `MockMvc`:
 
 TIP: If you need to configure elements of the auto-configuration (for example, when servlet filters should be applied) you can use attributes in the `@AutoConfigureMockMvc` annotation.
 
-If you use HtmlUnit or Selenium, auto-configuration also provides an HTMLUnit `WebClient` bean and/or a `WebDriver` bean.
+If you use HtmlUnit or Selenium, auto-configuration also provides an HtmlUnit `WebClient` bean and/or a Selenium `WebDriver` bean.
 The following example uses HtmlUnit:
 
 [source,java,indent=0]