Remove the cargo audit test

The cargo-audit version in the container is obsolete and no
longer working.

I've run this manually and it passes. Removing the test in this
branch.

Also bump coverage.

Signed-off-by: Adrian Catangiu <[email protected]>

Author: acatangiu

tests/integration_tests/build/test_coverage.py

@@ -19,7 +19,7 @@
 
 import host_tools.cargo_build as host  # pylint: disable=import-error
 
-COVERAGE_TARGET_PCT = 85.9
+COVERAGE_TARGET_PCT = 86.0
 COVERAGE_MAX_DELTA = 0.01
 
 CARGO_KCOV_REL_PATH = os.path.join(host.CARGO_BUILD_REL_PATH, 'kcov')