Fix to handle the exception for deletion of non-existing autofollow replication rule

Description

This PR handles the exception for deletion of any non-existing replication rule.

Earlier behaviour:

If any replication rule is tried to be deleted before creation of the first replication rule, it throws ResourceNotFoundException.

ex:

Directly delete the autofollow replication rule before creation of any autofollow rule.

curl -Method DELETE -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-Type' = 'application/json'} -body '{"leader_alias":"leader", "name": "dummy"}'

curl : { "error" : { "root_cause" : [ { "type" : "resource_not_found_exception", "reason" : "Metadata for leader:dummy doesn't exist" } ],     
"type" : "resource_not_found_exception", "reason" : "Metadata for leader:dummy doesn't exist" }, "status" : 404 }

Now, create a new replication rule 'A' and try to delete replication rule 'B'. Here we could see that there is a successful response in deleting a non-existing replication rule.

curl -Method POST -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-Typ
e' = 'application/json'} -body '{"leader_alias":"leader", "name": "test", "pattern": "test-*"}'                   

StatusCode        : 200
StatusDescription : OK
Content           : {
                      "acknowledged" : true
                    }

curl -Method DELETE -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-T
ype' = 'application/json'} -body '{"leader_alias":"leader", "name": "dummy"}'                             

StatusCode        : 200
StatusDescription : OK
Content           : {
                      "acknowledged" : true
                    }

Behaviour now:

Deletion of any non existing replication rule.

curl -Method DELETE -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-T
ype' = 'application/json'} -body '{"leader_alias":"leader", "name": "test"}'       
curl : { "error" : { "root_cause" : [ { "type" : "exception", "reason" : "Autofollow replication rule :leader:test does not exist" } ], "type" : "exception", 
"reason" : "Autofollow replication rule :leader:test does not exist" }, "status" : 500 }

Issues Resolved

https://github.com/opensearch-project/cross-cluster-replication/issues/1370

Check List

[ ] New functionality includes testing.
- [ ] All tests pass
[ ] New functionality has been documented.
- [ ] New functionality has javadoc added
[ ] Commits are signed per the DCO using --signoff

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Hi @monusingh-1 ,

Yes, the current behaviour as of now is as below:

Delete a non existing replication rule before the creation of any autofollow rule, then it returns 404

 curl -Method DELETE -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-T
ype' = 'application/json'} -body '{"leader_alias":"leader", "name": "test1"}'       
curl : { "error" : { "root_cause" : [ { "type" : "resource_not_found_exception", "reason" : "Metadata for leader:test1 doesn't exist" } ], "type" : 
"resource_not_found_exception", "reason" : "Metadata for leader:test1 doesn't exist" }, "status" : 404 }

But if there is any replication rule already there :

a) Create a replication rule "leader:test1"

curl -Method POST -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-Typ
e' = 'application/json'} -body '{"leader_alias":"leader", "name": "test1", "pattern": "test1"}'

StatusCode        : 200
StatusDescription : OK
Content           : {
                      "acknowledged" : true
                    }

b) Delete a non existing rule (say "leader:test2"), then the deletion of that replication rule returns 200.

  curl -Method DELETE -Uri "http://localhost:9201/_plugins/_replication/_autofollow?pretty"  -H @{'Content-T
ype' = 'application/json'} -body '{"leader_alias":"leader", "name": "test2"}'                                  

StatusCode        : 200
StatusDescription : OK
Content           : {
                      "acknowledged" : true
                    }

opensearch-project / cross-cluster-replication