Fix word wrapping determinism on BSD / Linux

fmt behaves totally differently depending on the version and on the
OS, use fold instead that has a consistent behaviour accross platform.

Tested with bazel test //scripts/release/... on OSX and Linux.

--
MOS_MIGRATED_REVID=101567574
diff --git a/scripts/release/release_test.sh b/scripts/release/release_test.sh
index 4c26068..3152054 100755
--- a/scripts/release/release_test.sh
+++ b/scripts/release/release_test.sh
@@ -195,8 +195,8 @@
   local header='Release v1 ('$(date +%Y-%m-%d)')
 
 Baseline: 1170dc6
-   + 0540fde: Extract version numbers that look like
-              "..._1.2.3_..." from BUILD_EMBED_LABEL into Info.plist.
+   + 0540fde: Extract version numbers that look like "..._1.2.3_..."
+              from BUILD_EMBED_LABEL into Info.plist.
 
 '
   assert_equals "${header}Test replacement" "$(cat ${TEST_log})"
@@ -208,8 +208,8 @@
   header='Release v1 ('$(date +%Y-%m-%d)')
 
 Baseline: 1170dc6
-   + 0540fde: Extract version numbers that look like
-              "..._1.2.3_..." from BUILD_EMBED_LABEL into Info.plist.
+   + 0540fde: Extract version numbers that look like "..._1.2.3_..."
+              from BUILD_EMBED_LABEL into Info.plist.
    + cef25c4: RELNOTES: Attribute error messages related to Android
               resources are easier to understand now.