Remove dead code modernization script (#6863)

scripts/modernize.sh

@@ -1,23 +0,0 @@
-#!/usr/bin/env bash
-
-set -o errexit
-set -o pipefail
-set -o nounset
-
-# Runs the Clang Modernizer in parallel on the code base.
-# Requires a compilation database in the build directory.
-
-find src include unit_tests -type f -name '*.hpp' -o -name '*.cpp' \
-  | xargs \
-      -I{} \
-      -P $(nproc) \
-      clang-modernize \
-        -p build \
-        -final-syntax-check \
-        -format \
-        -style=file \
-        -summary \
-        -for-compilers=clang-3.4,gcc-4.8 \
-        -include . \
-        -exclude third_party \
-      {}