Bug 1866976 - Fix new warnings from new shellcheck version. r=releng-reviewers,jcristau

TEST-UNEXPECTED-ERROR | /builds/worker/checkouts/gecko/taskcluster/docker/firefox-snap/runme.sh:77:75 | Double quote to prevent globbing and word splitting. (2086)
TEST-UNEXPECTED-ERROR | /builds/worker/checkouts/gecko/taskcluster/docker/funsize-update-generator/runme.sh:30:41 | Expansions inside ${..} need to be quoted separately, otherwise they match as patterns. (2295)

Differential Revision: https://phabricator.services.mozilla.com/D194854

taskcluster/docker/firefox-snap/runme.sh

@@ -74,7 +74,7 @@ done
 cp -v "$SCRIPT_DIRECTORY/tmpdir" "$SOURCE_DEST"
 
 # Generate snapcraft manifest
-sed -e "s/@VERSION@/${VERSION}/g" -e "s/@BUILD_NUMBER@/${BUILD_NUMBER}/g" ${PRODUCT}.snapcraft.yaml.in > "${WORKSPACE}/snapcraft.yaml"
+sed -e "s/@VERSION@/${VERSION}/g" -e "s/@BUILD_NUMBER@/${BUILD_NUMBER}/g" "${PRODUCT}.snapcraft.yaml.in" > "${WORKSPACE}/snapcraft.yaml"
 cd "${WORKSPACE}"
 
 # Make sure snapcraft knows we're building amd64, even though we may not be on this arch.

taskcluster/docker/funsize-update-generator/runme.sh

@@ -27,7 +27,7 @@ if [ -n "${S3_BUCKET_AND_PATH}" ] && getent hosts taskcluster
 then
   # Does this parse as we expect?
   S3_PATH=${S3_BUCKET_AND_PATH#*/}
-  AWS_BUCKET_NAME=${S3_BUCKET_AND_PATH%/${S3_PATH}*}
+  AWS_BUCKET_NAME=${S3_BUCKET_AND_PATH%/"${S3_PATH}"*}
   test "${S3_PATH}"
   test "${AWS_BUCKET_NAME}"