Made the licenses script output all problems (flutter#44223)

fixes: flutter/flutter#131680

verified the behavior in https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8773943493296876561/+/u/test:_licenses_check/stdout

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

ci/licenses.sh

@@ -4,7 +4,9 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-set -e
+# Do not exit when a non-zero return value is encountered to output all errors.
+# See: https://github.com/flutter/flutter/issues/131680
+# set -e
 shopt -s nullglob
 
 # Needed because if it is set, cd may print the path it changed to.
@@ -65,7 +67,7 @@ dart --version
 # Runs the tests for the license script.
 function run_tests() (
   cd "$SRC_DIR/flutter/tools/licenses"
-  find -name "*_test.dart" | xargs -n 1 dart --enable-asserts
+  find . -name "*_test.dart" | xargs -n 1 dart --enable-asserts
 )
 
 # Collects the license information from the repo.
@@ -91,7 +93,7 @@ function verify_licenses() (
   cd "$SRC_DIR"
 
   # These files trip up the script on Mac OS X.
-  find . -name ".DS_Store" -exec rm {} \;
+  find . -name ".DS_Store" -exec rm -f {} \;
 
   collect_licenses