Remove manual boxing from ftl, let the javac do it automatically

• Type: Story
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: 6.2.0 CE M4
• Fix Version/s: 6.2.0 CE M4
• Component/s: Core Infrastructure, Core Infrastructure > Service Builder, Performance
• Labels: None
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/8397

Javac has to take care all the autoboxing anyway.
No need to do them manually in ftl, remove them can make ftl looks simpler and let service builder run faster(very slightly).

The main goal is simplify ftls, easier to maintain.