Maxinum number of service mesh instances supported in ads mode

[nlgwcy]

What would you like to be added:
As BenchmarkClusterFlush Test, each cluster consume more than 40 inner_maps. Currently, the maximum number of inner_maps is MAP_SIZE_OF_OUTTER_MAP，that is a maxinum of 400 records can be stored. The governance rules of a service may involve multiple xDSs, such as listeners/router/cluster/... greatly limit the maximum number of service instances supported in the mesh.
Why is this needed:
Consider an optimized solution that supports a larger scale of service grid service instances.

[nlgwcy]

/assign nlgwcy

[hzxuzhonghu]

This is kind of a general problem, and some other maps have the same concern

[nlgwcy]

This is kind of a general problem, and some other maps have the same concern

yes, the size of ebpf maps need to be reviewed.