Use the Ext.ajax API call correctly.

[jpwhite4]

Description

The existing code used the half-baked CCR.encode function to try to
encode data for a rest call. This change uses the ExtJS library function
that encodes the parameters correctly.

Motivation and Context

Bug fix

Tests performed

Steps to reproduce / verify:

1. Create metric explorer chart with a '#' symbol in the chart title; Add some supremm data
2. Click show raw data in the chart; Click on a job in the "raw data" window and confirm that job viewer loads and has a search node with the aforementioned chart title.
3. Go back to the metric explorer and click on another job.
4. Confirm that the job viewer loads again and the second job appears under the same tree node as the first one (the buggy code would incorrectly create a duplicate search node).

Types of changes

• Bug fix (non-breaking change which fixes an issue)