[roll] Roll fuchsia [audio][assembly] legacy_driver_tools (8/11)

Add new granular virtual audio structured-config flags
- `virtual_audio: { legacy: True }`
- `legacy_driver_tools: True`
to Core, Terminal, and Workbench product configurations
(products/core/BUILD.bazel, products/terminal/BUILD.bazel,
products/workbench/platform_config.bzl).

This establishes the specific required virtual audio drivers and tools
for each product type without changing assembled image size yet (0 KiB
difference while `driver_tools` still contains migration values).

Once assembly rules cut over in CL 9/11, this configuration enables
Core to shed modern VAU, legacy VAU and driver utilities (320 KiB),
and enables Terminal to shed the modern virtual-audio driver and VAU
(64 KiB).

The overall intentions are to remove legacy aspects from modern
builds, remove modern aspects from older product builds and remove
easily-added tools from the base core build image.

In all these changes reduce the arm64 binary size of
- core builds:                       752 KiB
- minimal builds:                    466 KiB
- fuchsia_internal-based ENG builds: 466 KiB

Original-Original-Bug: 532663786
Test: build
CONV: 42088549-237a-4c45-9ab8-d2ec03192e2b
TAG: agy
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1748711
Original-Original-Revision: 6e05aeb3307545bf18123d80214644dae8412e44
GitOrigin-RevId: 0666dfbb6a8bea814d68070a44a7b88d91a9112f
Change-Id: I2e0d0be85a8ca826b22c0d806d3464d909806f98
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1773094
Cr-Commit-Position: refs/heads/main@{#199864}