ci: harden test selection and nightly coverage (#6341)

crates/e2e_test/src/protocols/README.md

@@ -11,10 +11,17 @@ test process directly.
 
 ## Running Tests
 
+Use the canonical CI-equivalent protocol command in the parent
+[`e2e_test` README](../../README.md#troubleshooting).
+
+For targeted debugging of the core suite only:
+
 ```bash
 RUSTFS_BUILD_FEATURES=ftps,webdav,sftp cargo test --package e2e_test test_protocol_core_suite -- --test-threads=1 --nocapture
 ```
 
+This targeted command does not cover the full `e2e-protocols` profile.
+
 `RUSTFS_BUILD_FEATURES` controls which features the test rustfs binary is
 built with. When this variable is set, the protocol test runner schedules
 only entries whose protocol is present in the requested feature list. Leave
@@ -133,4 +140,3 @@ property without consulting any external doc.
 Bind ports 9023 (SFTP) and 9100 (S3). Spawns rustfs with
 `RUSTFS_SFTP_IDLE_TIMEOUT=5`, sleeps 10 s past the timeout, then issues an
 SFTP request and asserts the server has closed the session.
-