Migrate gc code to AWS SDK v2

[nrb]

./cmd/clusterawsadm/cmd/gc
./cmd/clusterawsadm/cmd/gc/gc.go
./cmd/clusterawsadm/gc/gc.go
./cmd/clusterawsadm/gc/gc_test.go
./test/e2e/suites/gc_managed/gc_managed_test.go
./test/e2e/suites/gc_managed/gc_managed_suite_test.go
./test/e2e/suites/gc_unmanaged/gc_unmanaged_test.go
./test/e2e/suites/gc_unmanaged/gc_unmanaged_suite_test.go
./pkg/cloud/services/gc

[damdo]

See examples on how to migrate here: #5389

[Danil-Grigorev]

I have a try on this in #5518

/assign