Repository: quarkusio/quarkus
Issue: `YamlMetadataGenerator` emits yaml with line splits

### Describe the bug

The doc metadata yaml, which is generated by `YamlMetadataGenerator` contains blocks like this:
```
  - title: Infinispan Client Extension Reference Guide
    filename: infinispan-client-reference.adoc
    summary: "Infinispan is an in memory distributed data store and cache server that\\
      \\ offers flexible deployment options and robust capabilities for storing, managing,\\
      \\ and processing data."
```
https://github.com/quarkusio/quarkusio.github.io/blob/develop/_data/versioned/main/index/quarkus.yaml#L44-L48

I'm working on Japanese localization project https://github.com/quarkusio/ja.quarkus.io, and the localization tool `po4a` cannot parse the YAML that contains line splits.
(Please note it is not line breaks, it's line splits for formatting)
This issue prevents translating [the Guides index page](https://ja.quarkus.io/guides/).

The yaml is identical to this, and this representation can be parsed by po4a.
```
  - title: Infinispan Client Extension Reference Guide
    filename: infinispan-client-reference.adoc
    summary: "Infinispan is an in memory distributed data store and cache server that offers flexible deployment options and robust capabilities for storing, managing, and processing data."
```

It would nice if the `YamlMetadataGenerator` emits the yaml without line splits by disabling the Jackson Yaml's `YAMLGenerator.Feature.SPLIT_LINES`.

For more information, please refer the discussion in the Zulip chat: https://quarkusio.zulipchat.com/#narrow/stream/187030-users/topic/quarkus.2Eyaml.20on.20docs.20repo.20is.20bad.20indenting/near/326354873

### Expected behavior

`YamlMetadataGenerator` generates yaml without line splits.
```
  - title: Infinispan Client Extension Reference Guide
    filename: infinispan-client-reference.adoc
    summary: "Infinispan is an in memory distributed data store and cache server that offers flexible deployment options and robust capabilities for storing, managing, and processing data."
```

### Actual behavior

`YamlMetadataGenerator` generates yaml with line splits.
```
  - title: Infinispan Client Extension Reference Guide
    filename: infinispan-client-reference.adoc
    summary: "Infinispan is an in memory distributed data store and cache server that\\
      \\ offers flexible deployment options and robust capabilities for storing, managing,\\
      \\ and processing data."
```
https

### How to Reproduce?

Reproducer:

1. run `./mvnw -f docs clean install`
2. Please check the generated yaml `docs/target/indexByType.yaml`


### Output of `uname -a` or `ver`

_No response_

### Output of `java -version`

_No response_

### GraalVM version (if different from Java)

_No response_

### Quarkus version or git rev

0100232204b86ac87d9a373f6c2030a77bea1684

### Build tool (ie. output of `mvnw --version` or `gradlew --version`)

_No response_

### Additional information

_No response_

Changed files:
docs/src/main/java/io/quarkus/docs/generation/YamlMetadataGenerator.java

diff --git a/docs/src/main/java/io/quarkus/docs/generation/YamlMetadataGenerator.java b/docs/src/main/java/io/quarkus/docs/generation/YamlMetadataGenerator.java
index 79a46bdf22d..f7b6a52138f 100644
--- a/docs/src/main/java/io/quarkus/docs/generation/YamlMetadataGenerator.java
+++ b/docs/src/main/java/io/quarkus/docs/generation/YamlMetadataGenerator.java
@@ -108,7 +108,10 @@ public boolean test(String p) {
     }
 
     public void writeYamlFiles() throws StreamWriteException, DatabindException, IOException {
-        ObjectMapper om = new ObjectMapper(new YAMLFactory().enable(YAMLGenerator.Feature.MINIMIZE_QUOTES));
+        ObjectMapper om = new ObjectMapper(
+                new YAMLFactory()
+                        .enable(YAMLGenerator.Feature.MINIMIZE_QUOTES)
+                        .disable(YAMLGenerator.Feature.SPLIT_LINES));
         Map<String, DocMetadata> metadata = index.metadataByFile();
 
         om.writeValue(targetDir.resolve("indexByType.yaml").toFile(), index);