Support for excluding SQL statements from being captured

**Is your feature request related to a problem? Please describe.**
* We are using a connection pool when accessing our SQL database(s). On checkout we validate that the connection is (still) ok. As each validation sends a query to the database, each validation creates a span. So the validation creates many not so usefully spans which we want to get rid of.
* Some of our applications use transactions, sometimes even involving multiple databases. We also want to get rid of the resulting `PREPARE` AND `COMMIT` spans.

We hope to reduce the pressure on our APM servers by not sending these spans to them.

**Describe the solution you'd like**
I would like to have the possibility to ignore certain SQL statements from being captured. Basic wildcard matching would be sufficient for us. I already implemented a (JDBC only) solution for the Java agent: elastic/apm-agent-java#2293.

**Describe alternatives you've considered**
Right now we are dropping the spans when ingesting the events in Elasticsearch.