pytest: remove restaked.py test (#6198)

The test is quite flaky and it’s been decided that deleting it is the
best way forward since its value isn’t that high.

Fixes: #5503

nightly/README.md

@@ -80,7 +80,7 @@ optional `s`, `m` or `h` suffix.  If no suffix is given, `s` is
 assumed.  The default timeout is three minutes.  For example, the
 following increases timeout for a test to four minutes:
 
-    pytest --timeout=4m sanity/restaked.py
+    pytest --timeout=4m sanity/validator_switch.py
 
 `--release` makes the build use a release profile rather than a dev
 profile.  In other words, all `cargo` invocations are passed

nightly/pytest-sanity.txt

@@ -64,11 +64,6 @@ pytest --timeout=360 sanity/block_sync_archival.py
 pytest --timeout=360 sanity/block_sync_archival.py --features nightly_protocol,nightly_protocol_features
 pytest --timeout=240 sanity/validator_switch.py
 pytest --timeout=240 sanity/validator_switch.py --features nightly_protocol,nightly_protocol_features
-pytest --timeout=240 sanity/restaked.py
-# TODO(#4618): This is currently broken (even though non-nightly
-# works).  Comment out while we’re working on a fix / deciding whether
-# to remove them.
-#pytest --timeout=240 sanity/restaked.py --features nightly_protocol,nightly_protocol_features
 pytest --timeout=240 sanity/rpc_state_changes.py
 pytest --timeout=240 sanity/rpc_state_changes.py --features nightly_protocol,nightly_protocol_features
 pytest sanity/rpc_max_gas_burnt.py