Set the default value of `incompatible_disallow_conflicting_providers` to true

Fixes #5902

RELNOTES: `--incompatible_disallow_conflicting_providers` has been switched to true
PiperOrigin-RevId: 219143417
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
index 59da160..db78fb1 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
@@ -204,7 +204,7 @@
           .incompatibleDepsetUnion(false)
           .incompatibleDisableDeprecatedAttrParams(false)
           .incompatibleDisableObjcProviderResources(false)
-          .incompatibleDisallowConflictingProviders(false)
+          .incompatibleDisallowConflictingProviders(true)
           .incompatibleDisallowDataTransition(false)
           .incompatibleDisallowDictPlus(false)
           .incompatibleDisallowFileType(false)