Fix setting default title only when no subject has been set

[lezzago]

Signed-off-by: Ashish Agrawal ashisagr@amazon.com

Issue #, if available:
#529, #731
Description of changes:
Set default title only when there is no subject passed.

action message configuration example:

Current message look in chime:

Before Notification plugin introduction in chime:

With the fix look in chime:

With the fix for SNS:

CheckList:
[X] Commits are signed per the DCO using --signoff

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[opensearch-trigger-bot]

The backport to 2.5 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.5 2.5
# Navigate to the new working tree
cd .worktrees/backport-2.5
# Create a new branch
git switch --create backport/backport-750-to-2.5
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 830dff1d17c9a002efe417b55b84219b14c0c2fe
# Push it to GitHub
git push --set-upstream origin backport/backport-750-to-2.5
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.5

Then, create a pull request where the base branch is 2.5 and the compare/head branch is backport/backport-750-to-2.5.

[opensearch-trigger-bot]

The backport to 2.5 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.5 2.5
# Navigate to the new working tree
cd .worktrees/backport-2.5
# Create a new branch
git switch --create backport/backport-750-to-2.5
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 830dff1d17c9a002efe417b55b84219b14c0c2fe
# Push it to GitHub
git push --set-upstream origin backport/backport-750-to-2.5
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.5

Then, create a pull request where the base branch is 2.5 and the compare/head branch is backport/backport-750-to-2.5.