feat(dds): support dds instance set backup policy and switch seconds level monitoring

[SabreKeyZ]

…level monitoring

What this PR does / why we need it: support dds instance set backup policy and switch seconds level monitoring Which issue this PR fixes: (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged) fixes #xxx

Special notes for your reviewer:

Release note:

support dds instance set backup policy and switch seconds level monitoring

PR Checklist

• [X] Tests added/passed.
• [X] Documentation updated.
• [X] Schema updated.

Acceptance Steps Performed

 make testacc TEST='./huaweicloud/services/acceptance/dds/' TESTARGS='-run TestAccDDSV3Instance_withSecondsLevelMonitoring'
==> Checking that code complies with gofmt requirements... 
TF_ACC=1 go test ./huaweicloud/services/acceptance/dds/ -v -run TestAccDDSV3Instance_withSecondsLevelMonitoring -timeout 360m -parallel 4 
=== RUN   TestAccDDSV3Instance_withSecondLevelMonitoring 
=== PAUSE TestAccDDSV3Instance_withSecondLevelMonitoring 
=== CONT  TestAccDDSV3Instance_withSecondLevelMonitoring
--- PASS: TestAccDDSV3Instance_withSecondLevelMonitoring (1627.01s) 
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/dds       1627.050s

make testacc TEST='./huaweicloud/services/acceptance/dds/' TESTARGS='-ru
n TestAccDDSV3Instance_withBackupStrategy'                                                                         
==> Checking that code complies with gofmt requirements... 
TF_ACC=1 go test ./huaweicloud/services/acceptance/dds/ -v -run TestAccDDSV3Instance_withBackupStrategy -timeout 360m -parallel 4 
=== RUN   TestAccDDSV3Instance_withBackupStrategy 
=== PAUSE TestAccDDSV3Instance_withBackupStrategy
=== CONT  TestAccDDSV3Instance_withBackupStrategy
--- PASS: TestAccDDSV3Instance_withBackupStrategy (1643.77s) 
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/dds       1643.809s

[github-ci-robot]

This PR needs rebase.