Move root bzlmod sibling overrides into CI and compose defaults

[Copilot]

The root envoy-examples module had committed sibling local_path_override stanzas, unlike the sibling modules that keep MODULE.bazel publishable and inject overrides in CI. This makes the root module follow the same pattern while preserving local compose-based development.

• Root module

  • Removed committed sibling and commented upstream override stanzas from MODULE.bazel.
  • Kept published sibling dependencies as versioned bazel_deps.

• CI wiring

  • Added a _verify_examples.yml step to append sibling overrides during CI, after Bazel cache setup and before verification.

local_path_override(
    module_name = "envoy-example-filter-cc",
    path = "filter-cc",
)
local_path_override(
    module_name = "envoy-example-wasm-cc",
    path = "wasm-cc",
)

• Local development
  • Added default BAZEL_BUILD_EXTRA_OPTIONS for the examples compose service so local runs resolve sibling modules from the checkout by default.