### What does this PR do? Upgrade `bazel` from 8.6.0 to 9.0.1. ### Motivation Bazel 9.0.1 ships upstream fixes that directly benefit our build & developer experience: - bazelbuild/bazel#26842: `BUILD` files and `build` directories were incorrectly treated as the same entry on case-insensitive filesystems (e.g., Linux container running on a macOS host), causing spurious build failures (esp. for `rloader` we had to `gazelle`-exclude because of that), - bazelbuild/bazel#27695: a contribution of ours (also available in 8.6.0 as bazelbuild/bazel#28367) - nice to have when sharing a folder between a Linux host and a Windows VM through `virtiofs`, - bazelbuild/bazel#28640: another contribution of ours (@JSGette) - critical because it what preventing us from switching to Bazel 9 (ADMS config). ### Describe how you validated your changes `bazel test //...` passes. ### Additional Notes Groundwork landed in advance: - #47716 - #47745 - #47982 - #48016 - #48071 - #48082 - #48183 - #48186 - #48200 (>= Bazel 9 min) - #48201 (>= Bazel 9 min) - #48228 (>= Bazel 9 min) Co-authored-by: regis.desgroppes <regis.desgroppes@datadoghq.com>