[receiver/mysql] Add query sample collection for MySQL

[sincejune]

Description

This PR introduced query-level data collection for MySQL receiver in the logs pipeline.

We introduced Query Sample collection in this initial PR (Query samples are those queries which are currently running at the moment that scraper is working)

Configuration

We introduced 2 configurations for the feature(see receiver's README for details):

• events."db.server.query_sample".enabled: Flag to enable the feature.
• query_sample_collection.max_rows_per_query: The expected report numbers of queries sample in each scrape.

Example output"

resourceLogs:
  - resource: {}
    scopeLogs:
      - logRecords:
          - attributes:
              - key: db.system.name
                value:
                  stringValue: mysql
              - key: mysql.threads.thread_id
                value:
                  intValue: "1034384"
              - key: user.name
                value:
                  stringValue: myuser
              - key: db.namespace
                value:
                  stringValue: adventureworks
              - key: mysql.threads.processlist_command
                value:
                  stringValue: Query
              - key: mysql.threads.processlist_state
                value:
                  stringValue: executing
              - key: db.query.text
                value:
                  stringValue: SELECT soh.SalesOrderID, soh.OrderDate, c.CustomerID, p.Name AS ProductName, sod.OrderQty, sod.LineTotal FROM salesorderheader soh JOIN salesorderdetail sod ON soh.SalesOrderID = sod.SalesOrderID JOIN product p ON sod.ProductID = p.ProductID JOIN customer c ON soh.CustomerID = c.CustomerID ORDER BY soh.OrderDate DESC
              - key: mysql.events_statements_current.digest
                value:
                  stringValue: aaaaaa
              - key: mysql.event_id
                value:
                  intValue: "17470257762"
              - key: mysql.wait_type
                value:
                  stringValue: CPU
              - key: mysql.events_waits_current.timer_wait
                value:
                  doubleValue: 1.2851652e-05
              - key: client.address
                value:
                  stringValue: 192.168.1.80
              - key: client.port
                value:
                  intValue: "1234"
              - key: network.peer.address
                value:
                  stringValue: 192.168.1.80
              - key: network.peer.port
                value:
                  intValue: "1234"
            body: {}
            eventName: db.server.query_sample
            spanId: ""
            timeUnixNano: "1751033212422664000"
            traceId: ""
        scope:
          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/mysqlreceiver
          version: latest

Link to tracking issue

n/a

Testing

Added

Documentation

Added

[dmitryax]

LGTM

[dmitryax]

@antonblock, @ishleenk17 PTAL once you have a chance. This is the same approach that is being used in other database receivers to scrape similar events

[dmitryax]

It's been 3 weeks since the PR's open. I'm merging this