Flip --incompatible_remote_downloader_send_all_headers

Fixes #16356

RELNOTES[INC]: --incompatible_remote_downloader_send_all_headers is flipped to true. See #16356 for details.

Closes #16357.

PiperOrigin-RevId: 478506192
Change-Id: Id7b6e67c53fd4ec4455240ccbd40980c439b9a72

Author: Yannic

src/main/java/com/google/devtools/build/lib/remote/options/RemoteOptions.java

@@ -622,7 +622,7 @@ public RemoteOutputsStrategyConverter() {
 
   @Option(
       name = "incompatible_remote_downloader_send_all_headers",
-      defaultValue = "false",
+      defaultValue = "true",
       documentationCategory = OptionDocumentationCategory.REMOTE,
       effectTags = {OptionEffectTag.UNKNOWN},
       metadataTags = {OptionMetadataTag.INCOMPATIBLE_CHANGE},