Flip the default value of --incompatible_remove_enabled_toolchain_types to true.

This removes access to the "enabled_toolchain_types" property in the platform configuration fragment.

Fixes #10262.

RELNOTES[INC]: Flip --incompatible_remove_enabled_toolchain_types, so that rules can no longer access enabled toolchain types from the platform fragment.

PiperOrigin-RevId: 294913002
diff --git a/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java b/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
index f17274c..ec60aa2 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
@@ -502,7 +502,7 @@
 
   @Option(
       name = "incompatible_remove_enabled_toolchain_types",
-      defaultValue = "false",
+      defaultValue = "true",
       documentationCategory = OptionDocumentationCategory.STARLARK_SEMANTICS,
       effectTags = {OptionEffectTag.BUILD_FILE_SEMANTICS},
       metadataTags = {
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
index 2dca2f0..89d44c1 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
@@ -318,7 +318,7 @@
           .incompatibleNoRuleOutputsParam(false)
           .incompatibleNoSupportToolsInActionInputs(true)
           .incompatibleNoTargetOutputGroup(true)
-          .incompatibleRemoveEnabledToolchainTypes(false)
+          .incompatibleRemoveEnabledToolchainTypes(true)
           .incompatibleRunShellCommandString(false)
           .incompatibleRestrictNamedParams(true)
           .incompatibleVisibilityPrivateAttributesAtDefinition(false)