Flip --experimental_inprocess_symlink_creation.

RELNOTES: Symlink trees are now created through direct filesystem calls by default, instead of delegated to a helper process. On Windows, this entails respecting the `--windows_enable_symlinks` flag, falling back to a copy when the flag is unset (the helper process always attempts to create symlinks, irrespective of the flag). Set `--noexperimental_inprocess_symlink_creation` to temporarily revert to the previous behavior, which will be removed in a future release.
PiperOrigin-RevId: 671352606
Change-Id: Ie353a33bda4e7b642428bc2a77d733422a799086

Author: tjgq

src/main/java/com/google/devtools/build/lib/analysis/config/CoreOptions.java

@@ -884,12 +884,14 @@ public OutputPathsConverter() {
 
   @Option(
       name = "experimental_inprocess_symlink_creation",
-      defaultValue = "false",
+      defaultValue = "true",
       converter = BooleanConverter.class,
       documentationCategory = OptionDocumentationCategory.EXECUTION_STRATEGY,
       metadataTags = OptionMetadataTag.EXPERIMENTAL,
       effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS, OptionEffectTag.EXECUTION},
-      help = "Whether to make direct file system calls to create symlink trees")
+      help =
+          "Whether to make direct filesystem calls to create symlink trees instead of delegating"
+              + " to a helper process.")
   public boolean inProcessSymlinkCreation;
 
   @Option(