LogAudit: remove dynamic rate limiter

Select a low rate-limit to cut down on logspam and resulting
performance regressions.

Functionally reverts 247d682f
(logd: sepolicy dynamic rate limiting) and sets a static low
rate-limit. Before 247d682f, the limit was statically set to 20.
247d682f continued to support 20, but if sustained dropped the limit
to 5. This revert leaves us at 5 so as not to impact performance.

Test: /data/nativetest/logd-unit-tests/logd-unit-tests \
    --gtest_filter=logd.sepolicy_rate_limiter
    [  PASSED  ] 1 test.
Bug: 71538411
Change-Id: I6c92f4ba825cc24beb8f1f1b79258fa8097c837b