fix minor bug in remote monitor impl

[sbcd90]

Issue #, if available:
#1546

Description of changes:

CheckList:

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[eirsep]

https://github.com/opensearch-project/alerting/actions/runs/9706364641/job/26789918536?pr=1587
test failed

[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/alerting/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/alerting/backport-2.x
# Create a new branch
git switch --create backport-1587-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 22c5a29e18952c1d14d1635ee7e92748394d9bc8
# Push it to GitHub
git push --set-upstream origin backport-1587-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/alerting/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport-1587-to-2.x.

[opensearch-trigger-bot]

The backport to 2.15 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/alerting/backport-2.15 2.15
# Navigate to the new working tree
pushd ../.worktrees/alerting/backport-2.15
# Create a new branch
git switch --create backport-1587-to-2.15
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 22c5a29e18952c1d14d1635ee7e92748394d9bc8
# Push it to GitHub
git push --set-upstream origin backport-1587-to-2.15
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/alerting/backport-2.15

Then, create a pull request where the base branch is 2.15 and the compare/head branch is backport-1587-to-2.15.