Remove kythe task from presubmit.

Sometime it can be the bottleneck when other tasks are mostly cached.

I don't think kythe task in presubmit provides much value: they are built with `--keep_going` so the task is green even there are errors. People will probably never check the logs.

In case of breakage, we will get notified by the internal pipeline.

PiperOrigin-RevId: 702355117
Change-Id: I534603993949824e97045a8a7a84ad0b30066492

.bazelci/presubmit.yml

@@ -353,16 +353,6 @@ tasks:
     include_json_profile:
       - build
       - test
-  kythe_ubuntu2204:
-    shell_commands:
-    # Disable custom proto_toolchain_for_cc from kythe because it doesn't work with protobuf 29. See b/371908235.
-    # TODO(chiwang): Remove this once kythe resolves the issue.
-    - sed -i -e 's/build --proto_toolchain_for_cc=@kythe_release\/\/:cc_native_proto_toolchain//' /usr/local/kythe/extractors.bazelrc
-    index_flags:
-    - "--define=kythe_corpus=github.com/bazelbuild/bazel"
-    index_targets_query: "kind(\"cc_(binary|library|test|proto_library) rule\", ...) union kind(\"java_(binary|import|library|plugin|test|proto_library) rule\", ...) union kind(\"proto_library rule\", ...)"
-    index_upload_policy: Always
-    index_upload_gcs: False
   docs_ubuntu2004:
     platform: ubuntu2004
     name: "Docs"