Upgrade to Spring Boot 3.4.2 (#7215)

#### What type of PR is this?

/kind cleanup
/area core
/milestone 2.20.x

#### What this PR does / why we need it:

This PR upgrades to Spring Boot [3.4.2](https://github.com/spring-projects/spring-boot/releases/tag/v3.4.2).

Supersedes of <#7208>.

#### Does this PR introduce a user-facing change?

```release-note
升级依赖 Spring Boot 至 3.4.2
```

build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'org.springframework.boot' version '3.4.1' apply false
+    id 'org.springframework.boot' version '3.4.2' apply false
     id 'io.spring.dependency-management' version '1.1.7' apply false
     id "com.gorylenko.gradle-git-properties" version "2.4.1" apply false
     id "de.undercouch.download" version "5.6.0" apply false