<!--
if this PR closes one or more issues, you can automatically link the PR
with
them by using one of the [*linking
keywords*](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword),
e.g.
- this PR should close #xxxx
- fixes #xxxx
you can also mention related issues, PRs or discussions!
-->
Fixes#15528
# Description
Fixed `kv set` passing the pipeline input to the closure instead of the
value stored in that key.
# User-Facing Changes
Now `kv set` will pass the value in that key to the closure.
# Tests + Formatting
# After Submitting
# Description
Update some comments and fix potential security issue:
SQL Injection in DELETE statements: The code constructs SQL queries by
interpolating the $key variable directly into the string. If a key
contains malicious input could lead to SQL injection. Need to use
parameterized queries or escaping.
