Refactor how linux_x64_clang_debug uses Docker and scripts.

[ScottTodd]

Progress on #15332 and #18238 .

Similar to #18252, this drops a dependency on the build_tools/docker/docker_run.sh script. Unlike that PR, this goes a step further and also stops using build_tools/cmake/build_all.sh.

Functional changes:

• No more building iree-test-deps
  • We only get marginal value out of compiling test files using a debug compiler
  • Those tests are on the path to being moved to https://github.com/iree-org/iree-test-suites
• No more ccache
  • The debug build cache is too large for a local / GitHub Actions cache
  • I want to limit our reliance on the remote cache at http://storage.googleapis.com/iree-sccache/ccache (which uses GCP for storage and needs GCP auth)
  • Experiments show that this build is not significantly faster when using a cache, or at least dropping iree-test-deps provides equivalent time savings

Logs before: https://github.com/iree-org/iree/actions/runs/10417779910/job/28864909582 (96% cache hits, 9 minute build but 19 minutes total, due to iree-test-deps)
Logs after: https://github.com/iree-org/iree/actions/runs/10423409599/job/28870060781?pr=18255 (no cache, 11 minute build)

ci-exactly: linux_x64_clang_debug

[ScottTodd]

Here's a 2GB cache getting 11 / 5262 cache hits:
https://github.com/iree-org/iree/actions/runs/10411642302/job/28835942071#step:15:6

Soooo not possible using these cache settings and a local cache (backed up GitHub Actions Cache for save/restore). Might be able to use different settings like sccache or more compression, but it seems like the cache only saves 2 minutes on an 11 minute build for -DCMAKE_BUILD_TYPE=Debug anyways 🤷‍♂️

[marbre]

Reduced build time, yeah!

From an outsiders perspective it might not be obvious to understand why only building the project without running is useful. As the samples get build the compiler is used to compile those, but it may not be immediately clear. Thus, we could think about documenting what kind of workflows we're running why at some point.

[ScottTodd]

Reduced build time, yeah!

From an outsiders perspective it might not be obvious to understand why only building the project without running is useful. As the samples get build the compiler is used to compile those, but it may not be immediately clear. Thus, we could think about documenting what kind of workflows we're running why at some point.

https://iree.dev/developers/general/github-actions/#other-build-configurations

Other build configurations

These workflows build the full project from source using optional settings then run basic tests.

• Workflows in this category can use sanitizers, debug builds, alternate compilers, and other features that maintainers want automated coverage for.

For this 'debug' build, we sometimes see build issues only appear in debug (NDEBUG set/unset). Runtime failures unique to debug are also possible, but I think we could add a few smoketests for that instead of relying on building the iree-test-deps target.