Updated Auto Tune figures

Autotuned figures have been bumped in consultation with other community members as to a reasonable level. Please note these defaults are more on the one of each workers side than they are on the monolith Side.

roles/custom/matrix-synapse/defaults/main.yml

@@ -554,8 +554,8 @@ matrix_synapse_caches_global_factor: 10
 matrix_synapse_caches_expire_caches: true
 matrix_synapse_caches_cache_entry_ttl: 30m
 matrix_synapse_caches_sync_response_cache_duration: 2m
-matrix_synapse_caches_autotuning_max_cache_memory_usage: 1024M
-matrix_synapse_caches_autotuning_target_cache_memory_usage: 758M
+matrix_synapse_caches_autotuning_max_cache_memory_usage: 2048M
+matrix_synapse_caches_autotuning_target_cache_memory_usage: 1024M
 matrix_synapse_caches_autotuning_min_cache_ttl: 5m
 
 # Controls whether Synapse will federate at all.