Sandbox r8retrace genrules

r8retrace-run-retrace appears to already work with sandboxing.

r8retrace-dexdump-sample-app gets a diff in the output files due to
differing paths in sandboxed/non-sandboxed environments, but the
meaningful content is still the same.

Bug: 307824623
Test: ./build/soong/tests/genrule_sandbox_test.py r8retrace-dexdump-sample-app r8retrace-run-retrace
Change-Id: Ice0eeb762d35a4b32e8fb6d480ecf6d38959d0cc