Update extended_choice_param to use convert_xml()

Change-Id: Ia713a21061d6d6db1d1ac48983a44f6f3ea1cc1d

tests/parameters/fixtures/extended-choice-param-minimal.xml

@@ -7,7 +7,7 @@
           <name>OPTIONS</name>
           <description>Available options</description>
           <value>OptionA,OptionB,OptionC</value>
-          <visibleItemCount>2</visibleItemCount>
+          <visibleItemCount>5</visibleItemCount>
           <multiSelectDelimiter>,</multiSelectDelimiter>
           <quoteValue>false</quoteValue>
           <defaultValue/>

tests/parameters/fixtures/extended-choice-param-minimal.yaml

@@ -4,5 +4,3 @@ parameters:
       description: "Available options"
       type: 'PT_CHECKBOX'
       value: OptionA,OptionB,OptionC
-      visible-item-count: "2"
-

tests/parameters/fixtures/extended-choice-param003.xml

@@ -1,26 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<project>
-  <properties>
-    <hudson.model.ParametersDefinitionProperty>
-      <parameterDefinitions>
-        <com.cwctravel.hudson.plugins.extended__choice__parameter.ExtendedChoiceParameterDefinition>
-          <name>OPTIONS</name>
-          <description>Available options</description>
-          <value/>
-          <visibleItemCount>2</visibleItemCount>
-          <multiSelectDelimiter>,</multiSelectDelimiter>
-          <quoteValue>false</quoteValue>
-          <defaultValue>foo</defaultValue>
-          <descriptionPropertyValue>bar1, bar2, bar3</descriptionPropertyValue>
-          <type>PT_SINGLE_SELECT</type>
-          <propertyFile>/home/foo/property.prop</propertyFile>
-          <propertyKey>key</propertyKey>
-          <defaultPropertyFile>/home/property.prop</defaultPropertyFile>
-          <defaultPropertyKey>fookey</defaultPropertyKey>
-          <descriptionPropertyFile>/home/foo/bar.properties</descriptionPropertyFile>
-          <descriptionPropertyKey>bar_desc</descriptionPropertyKey>
-        </com.cwctravel.hudson.plugins.extended__choice__parameter.ExtendedChoiceParameterDefinition>
-      </parameterDefinitions>
-    </hudson.model.ParametersDefinitionProperty>
-  </properties>
-</project>

tests/parameters/fixtures/extended-choice-param003.yaml

@@ -1,13 +0,0 @@
-parameters:
-  - extended-choice:
-      name: OPTIONS
-      description: "Available options"
-      property-file: /home/foo/property.prop
-      property-key: key
-      visible-items: 2
-      default-value: foo
-      default-property-file: /home/property.prop
-      default-property-key: fookey
-      description-property-file: /home/foo/bar.properties
-      description-property-key: bar_desc
-      value-description: bar1, bar2, bar3