Add ContactsPicker to handheld system product packages behind a flag

The ContactsPicker app is included in PRODUCT_PACKAGES if RELEASE_ACONFIG_INCLUDE_CONTACTS_PICKER_APP build flag is set to true.

Flag: build.RELEASE_ACONFIG_INCLUDE_CONTACTS_PICKER_APP
Test: TH and locally
Bug: 437314846, 427934258
Change-Id: I8ead6eb118afe046dbb87dc070699d4608b30c8d