look into reducing fixed properties

**Is your feature request related to a problem? Please describe.**
A fixed property is one that requires restart of the related servers for a change to take effect. This is unavoidable in some cases depending on the property. However, when working on https://github.com/apache/accumulo/pull/5632 I saw several places where a fixed property could be made non-fixed.

**Describe the solution you'd like**
Look into all FIXED_PROPERTIES in Property and make as many non-fixed as we can.

**Additional context**
Related: https://github.com/apache/accumulo/pull/5632, https://github.com/apache/accumulo/issues/5693