Change name from platformprotos-prebuilt to platformprotos

tradefed-protos was built against with platformprotos(frameworks/base).
However, frameworks/base was missing in tradefed manifest, when the
module: platformprotos is missing, find the prebuilt version to build
agsinst.

Test: m -j tradefed-protos.
Bug: b/70351683
Change-Id: I86ba72adc773e2848dfae2181ded911431b059c3
Merged-In: I86ba72adc773e2848dfae2181ded911431b059c3