refactor fuzz-introspector command generation

This is to shorten the long line that runs fuzz-introspector and also in
anticipation that down the line we will have more oss-fuzz specific
commands in fuzz-introspector

infra/base-images/base-builder/compile

@@ -214,14 +214,22 @@ if [ "$SANITIZER" = "introspector" ]; then
   then
     cp $OUT/textcov_reports/*.covreport $SRC/inspector/
   fi  
-
-  if [[ -z "${COVERAGE_URL}" ]]; then
-    export COVERAGE_URL="/covreport/linux"
-  fi
 
   cd $SRC/inspector
+
+  # Correlate fuzzer binaries to fuzz-introspector's raw data
   python3 /fuzz-introspector/post-processing/main.py correlate --binaries_dir=$OUT/
-  python3 /fuzz-introspector/post-processing/main.py report --target_dir=$SRC/inspector --coverage_url=$COVERAGE_URL --correlation_file=exe_to_fuzz_introspector_logs.yaml
+
+  # Generate fuzz-introspector HTML report, this generates
+  # the file exe_to_fuzz_introspector_logs.yaml
+  REPORT_ARGS="--target_dir=$SRC/inspector"
+  # Only pass coverage_url when COVERAGE_URL is set (in cloud builds)
+  if [[ ! -z "${COVERAGE_URL+x}" ]]; then
+    REPORT_ARGS="$REPORT_ARGS --coverage_url=${COVERAGE_URL}"
+  fi
+  # Use the just-generated correlation file
+  REPORT_ARGS="$REPORT_ARGS --correlation_file=exe_to_fuzz_introspector_logs.yaml"
+  python3 /fuzz-introspector/post-processing/main.py report $REPORT_ARGS
 
   cp -rf $SRC/inspector $OUT/inspector
 fi