Core: Remove TableMetadata::Builder::resetMainBranch (apache#12149)

Co-authored-by: Sreesh Maheshwar <[email protected]>

Author: smaheshwar-pltr

core/src/main/java/org/apache/iceberg/TableMetadata.java

@@ -750,7 +750,7 @@ public TableMetadata buildReplacement(
 
     return new Builder(this)
         .upgradeFormatVersion(newFormatVersion)
-        .resetMainBranch()
+        .removeRef(SnapshotRef.MAIN_BRANCH)
         .setCurrentSchema(freshSchema, newLastColumnId.get())
         .setDefaultPartitionSpec(freshSpec)
         .setDefaultSortOrder(freshSortOrder)
@@ -1360,16 +1360,6 @@ public Builder removeRef(String name) {
       return this;
     }
 
-    private Builder resetMainBranch() {
-      this.currentSnapshotId = -1;
-      SnapshotRef ref = refs.remove(SnapshotRef.MAIN_BRANCH);
-      if (ref != null) {
-        changes.add(new MetadataUpdate.RemoveSnapshotRef(SnapshotRef.MAIN_BRANCH));
-      }
-
-      return this;
-    }
-
     /**
      * Set a statistics file for a snapshot.
      *