[Skymeld] Enable Skymeld by default.

#14057

PiperOrigin-RevId: 572493968
Change-Id: Ifbb1840eb54cea6777e142408b784703382eb4f0

Author: joeleba

src/main/java/com/google/devtools/build/lib/buildtool/BuildRequestOptions.java

@@ -375,7 +375,7 @@ public String getSymlinkPrefix(String productName) {
    */
   @Option(
       name = "experimental_merged_skyframe_analysis_execution",
-      defaultValue = "false",
+      defaultValue = "true",
       documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
       metadataTags = OptionMetadataTag.EXPERIMENTAL,
       effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS, OptionEffectTag.EXECUTION},