Adjust the MaxSinglePrimarySizeCondition version (#68553)

and re-enable BWC tests

build.gradle

@@ -169,8 +169,8 @@ tasks.register("verifyVersions") {
  * after the backport of the backcompat code is complete.
  */
 
-boolean bwc_tests_enabled = false
-String bwc_tests_disabled_issue = "https://github.com/elastic/elasticsearch/pull/68489" /* place a PR link here when committing bwc changes */
+boolean bwc_tests_enabled = true
+String bwc_tests_disabled_issue = "" /* place a PR link here when committing bwc changes */
 /*
  * FIPS 140-2 behavior was fixed in 7.11.0. Before that there is no way to run elasticsearch in a
  * JVM that is properly configured to be in fips mode with BCFIPS. For now we need to disable

rest-api-spec/src/main/resources/rest-api-spec/test/indices.rollover/35_max_single_primary_size_condition.yml

@@ -1,8 +1,8 @@
 ---
 "Rollover with max_single_primary_size condition":
   - skip:
-      version: " - 7.99.99"
-      reason: max_single_primary_size condition was introduced in 8.0.0
+      version: " - 7.11.99"
+      reason: max_single_primary_size condition was introduced in 7.12.0
 
   # create index with alias and replica
   - do:

server/src/main/java/org/elasticsearch/action/admin/indices/rollover/MaxSinglePrimarySizeCondition.java

@@ -67,6 +67,6 @@ public class MaxSinglePrimarySizeCondition extends Condition<ByteSizeValue> {
 
     @Override
     boolean includedInVersion(Version version) {
-        return version.onOrAfter(Version.V_8_0_0);
+        return version.onOrAfter(Version.V_7_12_0);
     }
 }