Some input XML in tests refer to nonexistent xsd

**Describe the bug**
Some tests attempt to does some XML namespace and schema setup in their input.
This is unnecessary and the schema is nonexistent. It also implies that QMCPACK inputs could be
not just well-formed XML but valid i.e. check against some schema. As far as I know that was never true.

This is not a bug per say for QMCPACK but if someone put our XML into a parser or editor that attempted to do validation this would create errors. It is also confusing to users and developers.

**To Reproduce**
open a performance test input

``` XML

```

**Remedy**

```XML

```