Cold-build cost of //src/ObjectUtils, before and after deleting LLVM.

Measured with the disk cache disabled so the action graph is genuinely
cold, and the repository cache shared so this measures compiling rather
than downloading:

  bazel build --disk_cache= //src/ObjectUtils:ObjectUtils

                                   wall   critical    actions
with LLVM (c7c4e6566)            158.7s      68.3s       3324
without LLVM                     104.6s      48.3s       2531
delta                              -34%       -29%       -793

The two LLVM patches went with it, so bazel/patches/ is down from three
to one, and MODULE.bazel loses a bazel_dep and an archive_override.