[PLAT-15970] Supporting HA across timezones

Summary: Issue with timezones not being stored in PG database so changing node timezone had weird effects on HA failovers. By storing the bigint directly we have no ambiguous conversion from pg timestamp to java timestamp and always rely on epoch millisecond time.

Test Plan:
Set up HA with active (A)/standby (B) on UTC

Change standby (B)  to America/Chicago

Promote standby (B)

Change new standby (A) from UTC to America/NewYork

Promote standby (A)

Reviewers: nsingh

Reviewed By: nsingh

Subscribers: sanketh, yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D41534

managed/src/main/java/com/yugabyte/yw/models/HighAvailabilityConfig.java

@@ -30,8 +30,6 @@
 import jakarta.persistence.Entity;
 import jakarta.persistence.Id;
 import jakarta.persistence.OneToMany;
-import jakarta.persistence.Temporal;
-import jakarta.persistence.TemporalType;
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.Date;
@@ -68,9 +66,7 @@ public class HighAvailabilityConfig extends Model {
   @JsonProperty("cluster_key")
   private String clusterKey;
 
-  @Temporal(TemporalType.TIMESTAMP)
-  @JsonProperty("last_failover")
-  private Date lastFailover;
+  private Long lastFailover;
 
   @OneToMany(mappedBy = "config", cascade = CascadeType.ALL)
   private List<PlatformInstance> instances;
@@ -80,15 +76,20 @@ public class HighAvailabilityConfig extends Model {
   private boolean acceptAnyCertificate;
 
   public void updateLastFailover(Date lastFailover) {
-    this.lastFailover = lastFailover;
+    this.lastFailover = lastFailover.getTime();
     this.update();
   }
 
   public void updateLastFailover() {
-    this.lastFailover = new Date();
+    this.lastFailover = new Date().getTime();
     this.update();
   }
 
+  @JsonProperty("last_failover")
+  public Date getLastFailover() {
+    return (this.lastFailover != null) ? new Date(this.lastFailover) : null;
+  }
+
   public void updateAcceptAnyCertificate(boolean acceptAnyCertificate) {
     this.acceptAnyCertificate = acceptAnyCertificate;
     this.update();

managed/src/main/resources/db/migration/default_/common/V391__Alter_High_Availability_lastFailover.sql

@@ -0,0 +1,6 @@
+-- Copyright (c) YugaByte, Inc.
+
+-- Change last_failover column from timestamp without tz to epoch time in ms
+ALTER TABLE high_availability_config
+ALTER COLUMN last_failover TYPE bigint
+USING (EXTRACT(EPOCH FROM last_failover) * 1000)::bigint;