PHPC-2086: Test against MongoDB 6.0 in Evergreen and revise matrices (#1332)
PHPC-2086: Test against MongoDB 6.0 in Evergreen and revise matrices (#1332)

Update axes definitions:
 * Add "mongodb" to version and edge-version axes names
 * Add MongoDB 6.0 to mongodb-versions axis
 * Fix latest-stable in mongodb-edge-versions axis (5.0 label was actually using MongoDB 4.0)
 * Bump latest-stable in php-edge-versions axis to PHP 8.1
 * Use debian11 for testing server versions not on debian92
 * Make RHEL host names consistent with those in mongo-php-toolchain
 * Fix label for zSeries (7.4 label was always using RHEL 7.2)

Revise test matrices:
 * Test all PHP versions with latest-stable MongoDB on Debian 11 and RHEL 7.0
 * Test all topologies and MongoDB versions with latest-stable PHP version on Debian
 * Restrict testing of ARM64, Power8, and zSeries architectures to MongoDB 4.4
 * Restrict testing of non-WiredTiger storage engines to MongoDB 4.0
 * Update mongodb-versions for OCSP, Stable API, and load balancer matrices
 * Use Debian 10 for OCSP testing (MongoDB 4.4+)
 * Use Debian 11 for Stable API testing (MongoDB 5.0+)
 * Keep Debian 9.2 for load balancer testing and remove MongoDB 6.0. Switch to Debian 11 once haproxy is available (see: BUILD-15237)

Use standalone-ssl, replicaset-auth, and sharded tasks for most matrices. The full set of tasks will be used for testing "all topologies and MongoDB versions".
jmikola/mongo-php-driver,mongodb/mongo-php-driver,mongodb/mongo-php-driver,mongodb/mongo-php-driver,jmikola/mongo-php-driver,jmikola/mongo-php-driver,mongodb/mongo-php-driver,jmikola/mongo-php-driver,jmikola/mongo-php-driver,mongodb/mongo-php-driver