Remove extra build/test flags. (#233)

They have been upstreamed into Buildkite config.
diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index b90a443..7a5d974 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -27,8 +27,3 @@
     - "--extra_execution_platforms=@bazel_toolchains//configs/ubuntu16_04_clang/1.1:nosla_xenial_docker"
     - "--host_platform=@bazel_toolchains//configs/ubuntu16_04_clang/1.1:nosla_xenial_docker"
     - "--platforms=@bazel_toolchains//configs/ubuntu16_04_clang/1.1:nosla_xenial_docker"
-    # TODO(xingao): Remove the flags below once in Buildkite setting.
-    - "--host_javabase=@bazel_toolchains//configs/ubuntu16_04_clang/latest:javabase"
-    - "--javabase=@bazel_toolchains//configs/ubuntu16_04_clang/latest:javabase"
-    - "--crosstool_top=@bazel_toolchains//configs/ubuntu16_04_clang/latest:crosstool_top_default"
-    - "--extra_toolchains=@bazel_toolchains//configs/ubuntu16_04_clang/latest:toolchain_default"