[GR-7234] Fix: Do not remove hidden active binding.

...iltin/src/com/oracle/truffle/r/nodes/builtin/base/Rm.java

.../oracle/truffle/r/nodes/access/BaseWriteVariableNode.java

...com/oracle/truffle/r/runtime/env/frame/ActiveBinding.java

...e/truffle/r/runtime/env/frame/REnvTruffleFrameAccess.java

....r.runtime/src/com/oracle/truffle/r/runtime/rng/RRNG.java

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

...rc/com/oracle/truffle/r/test/builtins/TestBuiltin_rm.java

...le.r.test/src/com/oracle/truffle/r/test/rng/TestRRNG.java