[PL-133028] alloy configuration for the mysql slow log

[PhilTaken]

@flyingcircusio/release-managers

PL-133028

based on #1264

Release process

• Created changelog entry using ./changelog.sh

PR release workflow (internal)

• PR has internal ticket
• internal issue ID (PL-…) part of branch name
• internal issue ID mentioned in PR description text
• ticket is on Platform agile board
• ticket state set to Pull request ready
• if ticket is more urgent than within the next few days, directly contact a member of the Platform team

Design notes

• Provide a feature toggle if the change might need to be adjusted/reverted quickly depending on context. Consider whether the default should be on or off. Example: rate limiting.
• All customer-facing features and (NixOS) options need to be discoverable from documentation. Add or update relevant documentation such that hosted and guided customers can understand it as well.

Security implications

• Security requirements defined? (WHERE)
• Security requirements tested? (EVIDENCE)

[sysvinit]

I haven't been writing changelogs for Loki-related platform features given that the integration is still considered WIP. But if you do leave it in, adding a ticket number would be nice.

[ctheune]

nit: there's multiple "weird" whitespace choices here ;)

[PhilTaken]

ah fair, I just copied the bulk of this from what alloy generated for the previous prometheus config and removed some fields that were not required or straight up caused issues when attempting to run it