[bazel] Remove --config=rbe

[aeubanks]

Summary

RBE is currently broken due to the RBE container being too old and not supporting C++17.
The bots have already stopped using --config=rbe.

The current plan is to use beefy machines and GCS remote caching.

utils/bazel/.bazelrc

 build:clang-cl --copt=/clang:-Wno-unused-const-variable --host_copt=/clang:-Wno-unused-const-variable
 
 # Disable some warnings hit even with `clang-cl` in Clang's own code.
 build:clang-cl --copt=/clang:-Wno-inconsistent-dllimport --host_copt=/clang:-Wno-inconsistent-dllimport
 build:clang-cl --cxxopt=/clang:-Wno-c++11-narrowing --host_cxxopt=/clang:-Wno-c++11-narrowing
 
 ###############################################################################
 
-###############################################################################
-# Configuration for building remotely using Remote Build Execution (RBE)
-# Based on https://github.com/bazelbuild/bazel-toolchains/blob/master/bazelrc/bazel-1.0.0.bazelrc
-###############################################################################
-
-build:rbe --remote_instance_name=projects/llvm-bazel/instances/default_instance
-
-# Depending on how many machines are in the remote execution instance, setting
-# this higher can make builds faster by allowing more jobs to run in parallel.
-# Setting it too high can result in jobs that timeout, however, while waiting
-# for a remote machine to execute them.
-build:rbe --jobs=150
-
-# Set several flags related to specifying the platform, toolchain and java
-# properties.
-# These flags should only be used as is for the rbe-ubuntu16-04 container
-# and need to be adapted to work with other toolchain containers.
-build:rbe --host_javabase=@rbe_default//java:jdk
-build:rbe --javabase=@rbe_default//java:jdk
-build:rbe --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8
-build:rbe --java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8
-build:rbe --crosstool_top=@rbe_default//cc:toolchain
-build:rbe --action_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
-# Platform flags:
-# The toolchain container used for execution is defined in the target indicated
-# by "extra_execution_platforms", "host_platform" and "platforms".
-# More about platforms: https://docs.bazel.build/versions/main/platforms.html
-build:rbe --extra_toolchains=@rbe_default//config:cc-toolchain
-build:rbe --extra_execution_platforms=@rbe_default//config:platform
-build:rbe --host_platform=@rbe_default//config:platform
-build:rbe --platforms=@rbe_default//config:platform
-
-build:rbe --define=EXECUTOR=remote
-
-# Enable remote execution so actions are performed on the remote systems.
-build:rbe --remote_executor=grpcs://remotebuildexecution.googleapis.com
-
-# Enforce stricter environment rules, which eliminates some non-hermetic
-# behavior and therefore improves both the remote cache hit rate and the
-# correctness and repeatability of the build.
-build:rbe --incompatible_strict_action_env=true
-
-# Set a higher timeout value, just in case.
-build:rbe --remote_timeout=3600
-
-# Local disk cache is incompatible with remote execution (for obvious reasons).
-build:rbe --disk_cache=""
-
-# Enable authentication. This will pick up application default credentials by
-# default. You can use --google_credentials=some_file.json to use a service
-# account credential instead.
-build:rbe --google_default_credentials=true
-
 # The user.bazelrc file is not checked in but available for local mods.
 # Always keep this at the end of the file so that user flags override.
 try-import %workspace%/user.bazelrc

utils/bazel/README.md

 The LLVM, MLIR, and Clang subprojects have configurations for Linux (Clang and
 GCC), Mac (Clang and GCC), and Windows (MSVC). Configuration options that are
 platform-specific are selected for in defines. Many are also hardcoded to the
 values currently used by all supported configurations. If there is a
 configuration you'd like to use that isn't supported, please send a patch.
 
 # Continuous Testing
 
-A [Buildkite pipeline](https://buildkite.com/llvm-project/upstream-bazel-rbe)
+A [Buildkite pipeline](https://buildkite.com/llvm-project/upstream-bazel)
 runs the full Bazel build on every commit to the main branch. Notifications of
 failures are sent to the
 [llvm-bazel-alerts google group](https://groups.google.com/g/llvm-bazel-alerts),
 which anyone is free to join. Currently, the behavior is just to send an email
 on each failure using Buildkite's built-in notification system, so if you
 subscribe, it is highly recommended that you set up email filters or some other
 mechanism to not flood your inbox. More sophisticated notifications, e.g. only
 on status change or routed based on blamelist are TODO (contributions welcome).

utils/bazel/WORKSPACE

 
 load("@llvm-raw//utils/bazel:vulkan_sdk.bzl", "vulkan_sdk_setup")
 
 maybe(
     vulkan_sdk_setup,
     name = "vulkan_sdk",
 )
 
-http_archive(
-    name = "bazel_toolchains",
-    sha256 = "1adf5db506a7e3c465a26988514cfc3971af6d5b3c2218925cd6e71ee443fc3f",
-    strip_prefix = "bazel-toolchains-4.0.0",
-    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/releases/download/4.0.0/bazel-toolchains-4.0.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-toolchains/releases/download/4.0.0/bazel-toolchains-4.0.0.tar.gz",
-    ],
-)
-
-load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
-
-rbe_autoconfig(name = "rbe_default")