danger: Make two commit guidelines warnings instead of errors

1. In some cases, it doesn't make sense to enforce a commit body when
   the changes changes many lines/files, but are very trivial (e.g. mass
   replacemnt/removal).
2. In some cases (e.g. when including stacktrace), it doesn't make sense
   to wrap lines, making it impossible to satisfy the "details line may
   not be longer than 72 characters".
Signed-off-by: Rémy Coutable <remy@rymai.me>

danger/commit_messages/Dangerfile

@@ -127,7 +127,7 @@ def warn_or_fail_commits(failed_linters, default_to_fail: true)
   Array(failed_linters).each do |linter|
     linter.problems.each do |problem_key, problem_desc|
       case problem_key
-      when :subject_too_short, :subject_above_warning
+      when :subject_too_short, :subject_above_warning, :details_too_many_changes, :details_line_too_long
         warn_commit(linter.commit, problem_desc)
       else
         self.__send__("#{level}_commit", linter.commit, problem_desc) # rubocop:disable GitlabSecurity/PublicSend

doc/development/contributing/merge_request_workflow.md

@@ -131,9 +131,9 @@ Commit messages should follow the guidelines below, for reasons explained by Chr
 - The commit subject must not be longer than 72 characters.
 - The commit subject must not end with a period.
 - The commit body must not contain more than 72 characters per line.
-- Commits that change 30 or more lines across at least 3 files must
-  describe these changes in the commit body.
 - The commit subject or body must not contain Emojis.
+- Commits that change 30 or more lines across at least 3 files should
+  describe these changes in the commit body.
 - Use issues and merge requests' full URLs instead of short references,
   as they are displayed as plain text outside of GitLab.
 - The merge request should not contain more than 10 commit messages.
@@ -178,7 +178,7 @@ Example commit message template that can be used on your machine that embodies t
 #    Do not end the subject line with a period
 #    Subject must contain at least 3 words
 #    Separate subject from body with a blank line
-#    Commits that change 30 or more lines across at least 3 files must
+#    Commits that change 30 or more lines across at least 3 files should
 #    describe these changes in the commit body
 #    Do not use Emojis
 #    Use the body to explain what and why vs. how