Set --legacy_important_outputs to false by default.

This flag reduces the largest proto size, which helps avoid sharp edges with remote execution systems (e.g., #12050).

RELNOTES[INC]: --legacy_important_outputs now has a default of false.

Closes #14353.

PiperOrigin-RevId: 449979885

src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventProtocolOptions.java

@@ -23,13 +23,13 @@
 public class BuildEventProtocolOptions extends OptionsBase {
 
   @Option(
-    name = "legacy_important_outputs",
-    defaultValue = "true",
-    documentationCategory = OptionDocumentationCategory.LOGGING,
-    effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
-    help = "Use this to suppress generation of the legacy important_outputs field in the "
-        + "TargetComplete event."
-  )
+      name = "legacy_important_outputs",
+      defaultValue = "false",
+      documentationCategory = OptionDocumentationCategory.LOGGING,
+      effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
+      help =
+          "Use this to suppress generation of the legacy important_outputs field in the "
+              + "TargetComplete event.")
   public boolean legacyImportantOutputs;
 
   @Option(