delay_destroy_frozen_sockets_version is rolled out to public 100%.
So this CL enables this flag as default with kill switch.
This flag is no-op if destroy_frozen_sockets_version is disabled, and
destroy_frozen_sockets_version is also rolled out to public 100%.
So this CL does not change any behabior on the production devices.
Upcoming CLs will update CS to destroy sockets of apps that are under
FIREWALL_CHAIN_BACKGROUND restriction as well.
So this CL renames flag name from delay_destroy_frozen_sockets_version
to delay_destroy_sockets which is not specific to frozen apps.
Bug: 300681644
Test: TH
Change-Id: Icb9edff4e517fca57408d7d690fe9e172754c35e
390be06f64