chore: use [lints] to address unexpected_cfgs lint (#7124)

Cargo.toml

@@ -17,3 +17,15 @@ members = [
 
 [workspace.metadata.spellcheck]
 config = "spellcheck.toml"
+
+[workspace.lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = [
+  'cfg(fuzzing)',
+  'cfg(loom)',
+  'cfg(mio_unsupported_force_poll_poll)',
+  'cfg(tokio_internal_mt_counters)',
+  'cfg(tokio_no_parking_lot)',
+  'cfg(tokio_no_tuning_tests)',
+  'cfg(tokio_taskdump)',
+  'cfg(tokio_unstable)',
+] }