Remove using preg_replace() on every query for PostgreSQL

Problem/Motivation

Connection::prepareStatement() in the pgsql driver runs preg_replace() on the full SQL of every prepared statement. The rewrite adds a ::text type-cast to fields used with the ILIKE and regex operators. This costs time for every statement, also for the many queries that use neither operator. A regex on the final SQL can also match inside expressions or string literals.

Proposed resolution

Add the cast when a condition is compiled instead. A new field_suffix directive in the condition operator map appends SQL to the field. The pgsql driver sets 'field_suffix' => '::text' for the LIKE and regex operators. Identity entries cover ILIKE and ~*, which the Views string filters use directly.

For SQL passed as a raw string, Connection::prepareStatement() keeps the rewrite behind a stripos() guard and triggers a deprecation. The rewrite is removed in Drupal 13.

Steps to reproduce

Profile any page on PostgreSQL. Connection::prepareStatement() runs the preg_replace() for every query.

Remaining tasks

Create the change record for the deprecation. Review.

API changes

Condition operator directives support a new field_suffix key. A new public method Connection::getConditionFieldSuffix() returns the suffix for an operator. Relying on the driver to cast fields in raw SQL strings is deprecated.

Data model changes

None.

For the committer

The changes to the .gitlab-ci.yml file need to be removed before merging!