test: remove public function to trigger semver breaking change

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: rluvaton

datafusion/common-runtime/src/lib.rs

@@ -33,9 +33,4 @@ pub use common::SpawnedTask;
 pub use join_set::JoinSet;
 pub use trace_utils::{
     JoinSetTracer, JoinSetTracerError, set_join_set_tracer, trace_block, trace_future,
-};
-
-/// Temporary public function to test semver breaking change detection.
-pub fn semver_test_function() -> &'static str {
-    "this will be removed to trigger a breaking change"
-}
+};