chore(e2e): scrub real IPs from harness docstring

Replace the test-bed IPs baked into the doc comment with placeholders.
Example-reproducible; no information leak.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: andrasbacsai

e2e-tests/src/lib.rs

@@ -4,12 +4,12 @@
 //! `#[ignore]` so default `cargo test` skips them. Run with:
 //!
 //! ```text
-//! BUILDER_HOST=78.47.80.33 \
-//! COOLD_ONLY_HOST=159.69.186.231 \
-//! BUILDER_MGMT=100.64.0.1 \
-//! COOLD_ONLY_MGMT=100.64.0.2 \
-//! CENTRAL_HOST=78.47.80.33 \
-//! SSH_KEY=~/.ssh/id_ed25519-no-pass \
+//! BUILDER_HOST=<host-a> \
+//! COOLD_ONLY_HOST=<host-b> \
+//! BUILDER_MGMT=<wg0-ip-of-host-a> \
+//! COOLD_ONLY_MGMT=<wg0-ip-of-host-b> \
+//! CENTRAL_HOST=<central-host> \
+//! SSH_KEY=~/.ssh/<key> \
 //! cargo test -p e2e-tests -- --ignored --test-threads=1
 //! ```
 //!