Denylist "bouncycastle-test-lib" to resolve build failures

aosp/2711135 adds `bouncycastle-test-lib` module, which is a
reverse dependency of the denylisted `bouncycastle`, causing
bp2build failure. This change denylists the module to resolve the
failure.

Test: TH
Bug: 297039097
Change-Id: Idbb8f5a17bd5727c53686ba16fe3ff1215e0d0ed