Filter certain control chars from db_qry_parse

For some long strings regsub seems faster.  String map faster for some short strings.
```
nscp 129> time { regsub -all {[\u0000-\u0004]+} $test "" }
28414 microseconds per iteration
nscp 130> time { string map {\u0000 "" \u0001 "" \u0002 "" \u0003 "" \u0004 ""} $test }
71702 microseconds per iteration
nscp 134> string length $test
2791629
```
```
nscp 138> time { regsub -all {[\u0000-\u0004]+} $test "" }
20 microseconds per iteration
nscp 139> time { string map {\u0000 "" \u0001 "" \u0002 "" \u0003 "" \u0004 ""} $test }
12 microseconds per iteration
nscp 140> string length $test
14

```