Problem

The sharding_stepdown_fcv_upgrade_downgrade_jscore_passthrough suite is extremely slow on debug aubsan variants, causing repeated timeouts. AUBSAN builds have significant runtime overhead due to sanitizer instrumentation, and this suite launches multiple mongod/mongos processes (sharding + stepdown + FCV upgrade/downgrade), which compounds the slowdown on default-sized distros.

Fix

Add the requires_large_host_aubsan tag so the suite runs on rhel8.8-xlarge when scheduled on aubsan variants. The additional CPU and memory should keep execution within timeout limits. No impact on other variants.

Additionally exclude this suite from the linux-debug-aubsan-compile-grpc variant due to resource intensiveness