message: Don't force a particular bazel version.
  The USE_BAZEL_VERSION appears to be unnecessarily strict enforcement
  of a particular bazel version when anything > 3.x.x should typically
  work.
diff: @@ -31,10 +31,8 @@ export BAZEL_CXXOPTS="-std=c++17"
  # Reduce the verbosity of progress output on CI
  export BAZEL_OPTS="-c opt --show_progress_rate_limit=10.0"
  +# Used to fetch the BAZEL version where needed.
  export BAZEL_VERSION=4.0.0
  -# Without following environment variable set, Bazel updates itself to the
  -# latest version
  -export USE_BAZEL_VERSION=$BAZEL_VERSION
  # TODO(b/171989992): revert to using release version after upgrading system
  # libraries/image (need: GLIBCXX_3.4.26, CXXABI_1.3.11, GLIBC_2.29).
  