Revert "JNI: Remove `JniMethodFast{Start,End}()`." This reverts commit 64d6e187f19ed670429652020561887e6b220216. Reason for revert: Breaks no-image JIT run tests (flaky). Bug: 172332525 Change-Id: I7813d89283eff0f6266318d3fb02d1257471798d