VAULT-5827 Don't prepare SQL queries before executing them
We don't support proper prepared statements, i.e., preparing once and
executing many times since we do our own templating. So preparing our
queries does not really accomplish anything, and can have severe
performance impacts (see
https://github.com/hashicorp/vault-plugin-database-snowflake/issues/13
for example).
This behavior seems to have been copy-pasted for many years but not for
any particular reason that we have been able to find. First use was in
https://github.com/hashicorp/vault/pull/15
So here we switch to new methods suffixed with `Direct` to indicate
that they don't `Prepare` before running `Exec`, and switch everything
here to use those. We maintain the older methods with the existing
behavior (with `Prepare`) for backwards compatibility.
This also temporarily disables couchbase, elasticsearch, and
mongodbatlas because the `Serve` function needs to change signatures
and those plugins are vendored in from external repos, causing problems
when building.
* fix: rotate root credentials for database plugins using WAL
* test: adds a test for WAL rollback logic
* fix: progress on wal rollback
* docs: updates some comments
* docs: updates some comments
* test: adds additional test coverage for WAL rollback
* chore: remove unneeded log
* style: error handling, imports, signature line wraps
* fix: always close db plugin connection
