pb-4241: Added ErrCodeBucketAlreadyExists check in CreateBucket to avoid logging confusing warning event in the applicationbackup CR.

[siva-portworx]

What type of PR is this?

Uncomment only one and also add the corresponding label in the PR:
bug

What this PR does / why we need it:

pb-4241: Added ErrCodeBucketAlreadyExists check in CreateBucket to avoid logging confusing warning event in the applicationbackup CR.

Does this PR change a user-facing CRD or CLI?:

Is a release note needed?:

Issue: Warning event is logged in the applicaitonbackup CR, if the S3 bucket was already exists.
User Impact: The warning event was confusing to the user.
Resolution: Avoiding warning event if S3 objectstore gives ErrCodeBucketAlreadyExists code.

Does this change need to be cherry-picked to a release branch?:
23.7.2 branch

Testing:
Before fix:

After fix the warning event is visible in applicationbackup CR.

[cnbu-jenkins]

Can one of the admins verify this patch?