avoid issues while linking shared libraries with Rust test binaries.
This change is made to avoid vts-tradefed failure to link the shared
library while running the Rust VTS `keystore2_client_tests` test
suite. As suggested in b/314110490#24 using the libkeystore-engine
static-library to run keystore2_client_tests.
Bug: 314110490, 298668920
Test: atest keystore2_client_tests; run vts -m keystore2_client_tests
Change-Id: If956865eeb4af908f33b1ad81a2b2e26300aae0e