Setting empty property value via the shell deletes the property

[ddanielr]

Describe the bug
Setting a table property to an empty string deletes the property from ZK vs overriding the value to an empty string.

This was verified by using the accumulo admin dumpConfig -a tool to pull down the table configs and verify that the property no longer existed as a per-table override

Versions (OS, Maven, Java, and others, as appropriate):

• Affected version(s) of this project: [e.g. 1.10.0] 2.1.x
• OS: [e.g. CentOS 7.5] centos 7
• Others:

Expected behavior
The property value is overridden to an empty string and is only deleted if the -d flag is used.

Additional context
@ctubbsii had some ideas on why this was happening

[ddanielr]

@sparkyy34 discovered this bug if there are any more questions.

[ctubbsii]

@jmark99 are you working on this?

[jmark99]

@ctubbsii yes. Started looking this week. Should have a PR early next week as I'm away the rest of this week.