Drop unused Symbolic Execution debugging rules

These rules were introduced in SONARJAVA-2555, while extensively working on cross-file symbolic execution engine. Since then, these rules have not been used at all, or extremely occasionally.

With the evolution of the symbolic execution engine (dropped byte-code-based SE engine) and a possible future decommission in favor of a more powerful approach, these rules are now obsolete and should be removed, with their activation logic.