Fix integration test failure by allowing direct access to system index warning

[gaobinlong]

Description

Fix the integration test failure of org.opensearch.integtest.config.ChimeNotificationConfigCrudIT which throws org.opensearch.client.WarningFailureException when refreshing all the indices in the test cluster, the change of this PR is that only refresh the system index .opensearch-notification-config in this plugin and allow the warning when refreshing the index.

Issues Resolved

#783

Check List

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[Hailong-am]

bwc will not pass on main until we bump the bwc version to 2.12

[Hailong-am]

test the changes on my local rpm package with command ./gradlew integTest -Dtests.rest.cluster="localhost:9200" -Dtests.cluster="localhost:9200" -Dtests.clustername="opensearch-integrationtest" -Dhttps=false, it works well.

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/notifications/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/notifications/backport-2.x
# Create a new branch
git switch --create backport/backport-784-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 0a7a5f99e71248cce9d5c15b0b99f9f270261d21
# Push it to GitHub
git push --set-upstream origin backport/backport-784-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/notifications/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-784-to-2.x.

[opensearch-trigger-bot]

The backport to 2.11 failed:

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

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/notifications/backport-2.11 2.11
# Navigate to the new working tree
pushd ../.worktrees/notifications/backport-2.11
# Create a new branch
git switch --create backport/backport-784-to-2.11
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 0a7a5f99e71248cce9d5c15b0b99f9f270261d21
# Push it to GitHub
git push --set-upstream origin backport/backport-784-to-2.11
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/notifications/backport-2.11

Then, create a pull request where the base branch is 2.11 and the compare/head branch is backport/backport-784-to-2.11.