Run Bazel inside shell tests with --nohome_rc --nosystem_rc.

This prevents the test from accidentally passing or failing due to
the state of any $HOME/.bazelrc or system-wide bazelrc files.

Author: philwo

src/test/shell/bin/bazel

@@ -23,4 +23,4 @@ bazel_bin=$(rlocation io_bazel/src/bazel)
 unset RUNFILES_DIR
 unset RUNFILES_MANIFEST_FILE
 unset RUNFILES_MANIFEST_ONLY
-exec $bazel_bin --bazelrc=$TEST_TMPDIR/bazelrc "$@"
+exec $bazel_bin --nohome_rc --nosystem_rc --bazelrc=$TEST_TMPDIR/bazelrc "$@"