Adjust IndexRequest#isPipelineResolved BWC

This commit adjusts the BWC version for IndexRequest#isPipelineResolved
after the required pipeline work was backported to 7.x.

server/src/main/java/org/elasticsearch/action/index/IndexRequest.java

@@ -126,7 +126,7 @@ public class IndexRequest extends ReplicatedWriteRequest<IndexRequest> implement
         version = in.readLong();
         versionType = VersionType.fromValue(in.readByte());
         pipeline = in.readOptionalString();
-        if (in.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (in.getVersion().onOrAfter(Version.V_7_5_0)) {
             isPipelineResolved = in.readBoolean();
         }
         isRetry = in.readBoolean();
@@ -651,7 +651,7 @@ public class IndexRequest extends ReplicatedWriteRequest<IndexRequest> implement
         out.writeLong(version);
         out.writeByte(versionType.getValue());
         out.writeOptionalString(pipeline);
-        if (out.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (out.getVersion().onOrAfter(Version.V_7_5_0)) {
             out.writeBoolean(isPipelineResolved);
         }
         out.writeBoolean(isRetry);