Revert "[AST] Add generator for source location introspection"

Breaks the build ... somehow: https://llvm-compile-time-tracker.com/show_error.php?commit=77f7d2be214a1de29d583c75739f563593991fc3

FAILED: tools/clang/include/clang/Tooling/NodeIntrospection.inc
cd /root/llvm-compile-time-tracker/llvm-project-build/tools/clang/lib/Tooling && /usr/bin/cmake -E make_directory /root/llvm-compile-time-tracker/llvm-project-build/tools/clang/lib/Tooling/generated/ && /root/llvm-compile-time-tracker/llvm-project/clang/lib/Tooling/DumpTool/generate_cxx_src_locs.py --json-input-path /root/llvm-compile-time-tracker/llvm-project-build/ASTNodeAPI.json --output-file generated/NodeIntrospection.inc --empty-implementation 0 && /usr/bin/cmake -E copy_if_different /root/llvm-compile-time-tracker/llvm-project-build/tools/clang/lib/Tooling/generated/NodeIntrospection.inc /root/llvm-compile-time-tracker/llvm-project-build/tools/clang/include/clang/Tooling/NodeIntrospection.inc
/bin/sh: 1: /root/llvm-compile-time-tracker/llvm-project/clang/lib/Tooling/DumpTool/generate_cxx_src_locs.py: not found

This reverts commit cefe7111.
This reverts commit f72f122f.
This reverts commit 970c21e3.
This reverts commit 77f7d2be.