rngtest: Improve robustness and ensure correct CI exit codes

- Switch random input collection from cat to dd for reliability.
- Always remove temp files after test run.
- Add consistent exit 0 (PASS) or exit 1 (FAIL) for every outcome.
- Improve error handling on missing dependencies, entropy, and output.
- Log failures for all possible test aborts to aid CI debugging.

Signed-off-by: Srikanth Muppandam <[email protected]>

Author: smuppand

Runner/suites/Kernel/FunctionalArea/baseport/rngtest/run.sh

@@ -83,11 +83,13 @@ log_info "rngtest: FIPS 140-2 successes = $successes"
 if [ "$successes" -ge 10 ]; then
     log_pass "$TESTNAME : Test Passed ($successes FIPS 140-2 successes)"
     echo "$TESTNAME PASS" > "$res_file"
+    rm -f "$TMP_BIN" "$TMP_OUT"
+    exit 0
 else
     log_fail "$TESTNAME : Test Failed ($successes FIPS 140-2 successes)"
     echo "$TESTNAME FAIL" > "$res_file"
+    rm -f "$TMP_BIN" "$TMP_OUT"
+    exit 1
 fi
 
-rm -f "$TMP_BIN" "$TMP_OUT"
-
 log_info "-------------------Completed $TESTNAME Testcase----------------------------"