Update check_format_compatible.sh for default format_version=4 (#6594)

Summary:
And add releases that should have been added before (6.6 - 6.8)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6594

Test Plan: facebook automated test (so much easier than running myself)

Reviewed By: riversand963

Differential Revision: D20649106

Pulled By: pdillinger

fbshipit-source-id: 78832449d9295580282cebf117e3968362fbdc69

tools/check_format_compatible.sh

@@ -55,9 +55,9 @@ EOF
 
 declare -a backward_compatible_checkout_objs=("2.2.fb.branch" "2.3.fb.branch" "2.4.fb.branch" "2.5.fb.branch" "2.6.fb.branch" "2.7.fb.branch" "2.8.1.fb" "3.0.fb.branch" "3.1.fb" "3.2.fb" "3.3.fb" "3.4.fb" "3.5.fb" "3.6.fb" "3.7.fb" "3.8.fb" "3.9.fb")
 declare -a forward_compatible_checkout_objs=("4.2.fb" "4.3.fb" "4.4.fb" "4.5.fb" "4.6.fb" "4.7.fb" "4.8.fb" "4.9.fb" "4.10.fb" "4.11.fb" "4.12.fb" "4.13.fb" "5.0.fb" "5.1.fb" "5.2.fb" "5.3.fb" "5.4.fb" "5.5.fb" "5.6.fb" "5.7.fb" "5.8.fb" "5.9.fb" "5.10.fb")
-declare -a forward_compatible_with_options_checkout_objs=("5.11.fb" "5.12.fb" "5.13.fb" "5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb")
+declare -a forward_compatible_with_options_checkout_objs=("5.11.fb" "5.12.fb" "5.13.fb" "5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb" "6.6.fb" "6.7.fb" "6.8.fb")
 declare -a checkout_objs=(${backward_compatible_checkout_objs[@]} ${forward_compatible_checkout_objs[@]} ${forward_compatible_with_options_checkout_objs[@]})
-declare -a extern_sst_ingestion_compatible_checkout_objs=("5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb")
+declare -a extern_sst_ingestion_compatible_checkout_objs=("5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb" "6.6.fb" "6.7.fb" "6.8.fb")
 
 generate_db()
 {