Move the host preparer to the plan file instead of module test xml

Based on other code references, it looks like that should be outside of
the module test xml and included as a plan, otherwise the sdk-tar option
is not recognized.

Bug: 302034872
Change-Id: Ie39f871fa959568f7fd39a4c44e3b96712a18f47
Test: n/a
Flag: n/a