[opt](memory) Move schemaHash from Replica to LocalReplica

schemaHash in the base Replica class wastes 4 bytes per CloudReplica.
Cloud storage paths don't use schema_hash, and callers like
MetadataViewer already guard with getSchemaHash() != -1.

This follows the same pattern as dbId removal in #62079.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dataroaring

fe/fe-core/src/main/java/org/apache/doris/catalog/LocalReplica.java

@@ -30,6 +30,7 @@ public class LocalReplica extends Replica {
 
     @SerializedName(value = "bid", alternate = {"backendId"})
     private long backendId;
+    private int schemaHash = -1;
 
     @SerializedName(value = "rds", alternate = {"remoteDataSize"})
     private volatile long remoteDataSize = 0;
@@ -129,6 +130,7 @@ public LocalReplica(long replicaId, long backendId, long version, int schemaHash
         super(replicaId, backendId, version, schemaHash, dataSize, remoteDataSize, rowCount, state, lastFailedVersion,
                 lastSuccessVersion);
         this.backendId = backendId;
+        this.schemaHash = schemaHash;
         this.lastFailedVersion = lastFailedVersion;
         if (this.lastFailedVersion > 0) {
             this.lastFailedTimestamp = System.currentTimeMillis();
@@ -157,6 +159,16 @@ public void setBackendId(long backendId) {
         this.backendId = backendId;
     }
 
+    @Override
+    public int getSchemaHash() {
+        return schemaHash;
+    }
+
+    @Override
+    public void setSchemaHash(int schemaHash) {
+        this.schemaHash = schemaHash;
+    }
+
     @Override
     public long getLastFailedVersion() {
         return lastFailedVersion;

fe/fe-core/src/main/java/org/apache/doris/catalog/Replica.java

@@ -88,7 +88,6 @@ public static class ReplicaContext {
     // the version could be queried
     @SerializedName(value = "v", alternate = {"version"})
     protected volatile long version;
-    private int schemaHash = -1;
     @SerializedName(value = "ds", alternate = {"dataSize"})
     private volatile long dataSize = 0;
     @SerializedName(value = "rc", alternate = {"rowCount"})
@@ -129,7 +128,6 @@ public Replica(long replicaId, long backendId, long version, int schemaHash,
                        long lastSuccessVersion) {
         this.id = replicaId;
         this.version = version;
-        this.schemaHash = schemaHash;
 
         this.dataSize = dataSize;
         this.rowCount = rowCount;
@@ -144,12 +142,12 @@ public long getVersion() {
     }
 
     public int getSchemaHash() {
-        return schemaHash;
+        return -1;
     }
 
     // for compatibility
     public void setSchemaHash(int schemaHash) {
-        this.schemaHash = schemaHash;
+        // no-op in base class; overridden in LocalReplica
     }
 
     public long getId() {
@@ -428,7 +426,7 @@ public String toString() {
         strBuffer.append(", lastFailedTimestamp=");
         strBuffer.append(getLastFailedTimestamp());
         strBuffer.append(", schemaHash=");
-        strBuffer.append(schemaHash);
+        strBuffer.append(getSchemaHash());
         strBuffer.append(", state=");
         strBuffer.append(state.name());
         strBuffer.append(", isBad=");